diff --git a/build.gradle b/build.gradle
index d6a60fa9e37..486220cf22e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -29,7 +29,7 @@ dependencies {
 	shadow group: 'org.bstats', name: 'bstats-bukkit', version: '3.0.2'
 	shadow group: 'net.kyori', name: 'adventure-text-serializer-bungeecord', version: '4.3.2'
 
-	implementation group: 'io.papermc.paper', name: 'paper-api', version: '1.20.6-R0.1-SNAPSHOT'
+	implementation group: 'io.papermc.paper', name: 'paper-api', version: '1.21-R0.1-SNAPSHOT'
 	implementation group: 'org.eclipse.jdt', name: 'org.eclipse.jdt.annotation', version: '2.2.700'
 	implementation group: 'com.google.code.findbugs', name: 'findbugs', version: '3.0.1'
 	implementation group: 'com.sk89q.worldguard', name: 'worldguard-legacy', version: '7.0.0-SNAPSHOT'
@@ -235,7 +235,7 @@ def java21 = 21
 def java17 = 17
 def java11 = 11
 
-def latestEnv = 'java21/paper-1.20.6.json'
+def latestEnv = 'java21/paper-1.21.0.json'
 def latestJava = java21
 def oldestJava = java11
 
diff --git a/gradle.properties b/gradle.properties
index f78ae1766eb..469d1e072ce 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -7,5 +7,5 @@ groupid=ch.njol
 name=skript
 version=2.8.7
 jarName=Skript.jar
-testEnv=java21/paper-1.20.6
+testEnv=java21/paper-1.21.0
 testEnvJavaVersion=21
diff --git a/src/main/java/ch/njol/skript/aliases/AliasesProvider.java b/src/main/java/ch/njol/skript/aliases/AliasesProvider.java
index a3b8b215b75..cccf91618ed 100644
--- a/src/main/java/ch/njol/skript/aliases/AliasesProvider.java
+++ b/src/main/java/ch/njol/skript/aliases/AliasesProvider.java
@@ -304,16 +304,19 @@ public void addAlias(AliasName name, String id, @Nullable Map<String, Object> ta
 			}
 			
 			// Apply (NBT) tags to item stack
-			ItemStack stack = new ItemStack(material);
+			ItemStack stack = null;
 			int itemFlags = 0;
-			if (tags != null) {
-				itemFlags = applyTags(stack, new HashMap<>(tags));
+			if (material.isItem()) {
+				stack = new ItemStack(material);
+				if (tags != null) {
+					itemFlags = applyTags(stack, new HashMap<>(tags));
+				}
 			}
 			
 			// Parse block state to block values
 			BlockValues blockValues = BlockCompat.INSTANCE.createBlockValues(material, blockStates, stack, itemFlags);
 			
-			ItemData data = new ItemData(stack, blockValues);
+			ItemData data = stack != null ? new ItemData(stack, blockValues) : new ItemData(material, blockValues);
 			data.isAlias = true;
 			data.itemFlags = itemFlags;
 			
diff --git a/src/main/java/ch/njol/skript/aliases/ItemData.java b/src/main/java/ch/njol/skript/aliases/ItemData.java
index 32323c57e6f..0f68279f43a 100644
--- a/src/main/java/ch/njol/skript/aliases/ItemData.java
+++ b/src/main/java/ch/njol/skript/aliases/ItemData.java
@@ -37,7 +37,7 @@
 import org.bukkit.inventory.ItemFlag;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;
-import org.eclipse.jdt.annotation.Nullable;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
 import java.io.NotSerializableException;
@@ -91,11 +91,6 @@ public static class OldItemData {
 	@Deprecated
 	public static final boolean itemDataValues = false;
 	
-	/**
-	 * ItemStack, which is used for everything but serialization.
-	 */
-	transient ItemStack stack;
-	
 	/**
 	 * Type of the item as Bukkit material. Serialized manually.
 	 */
@@ -105,14 +100,18 @@ public static class OldItemData {
 	 * If this represents all possible items.
 	 */
 	boolean isAnything;
-	
+
+	/**
+	 * ItemStack, which is used for everything but serialization.
+	 */
+	transient @Nullable ItemStack stack;
+
 	/**
 	 * When this ItemData represents a block, this contains information to
 	 * allow comparing it against other blocks.
 	 */
-	@Nullable
-	BlockValues blockValues;
-	
+	@Nullable BlockValues blockValues;
+
 	/**
 	 * Whether this represents an item (that definitely cannot have
 	 * block states) or a block, which might have them.
@@ -140,9 +139,10 @@ public static class OldItemData {
 	
 	public ItemData(Material type, @Nullable String tags) {
 		this.type = type;
-		
-		this.stack = new ItemStack(type);
-		this.blockValues = BlockCompat.INSTANCE.getBlockValues(stack);
+
+		if (type.isItem())
+			this.stack = new ItemStack(type);
+		this.blockValues = BlockCompat.INSTANCE.getBlockValues(type);
 		if (tags != null) {
 			applyTags(tags);
 		}
@@ -150,8 +150,9 @@ public ItemData(Material type, @Nullable String tags) {
 	
 	public ItemData(Material type, int amount) {
 		this.type = type;
-		this.stack = new ItemStack(type, Math.abs(amount));
-		this.blockValues = BlockCompat.INSTANCE.getBlockValues(stack);
+		if (type.isItem())
+			this.stack = new ItemStack(type, Math.abs(amount));
+		this.blockValues = BlockCompat.INSTANCE.getBlockValues(type);
 	}
 	
 	public ItemData(Material type) {
@@ -159,13 +160,18 @@ public ItemData(Material type) {
 	}
 	
 	public ItemData(ItemData data) {
-		this.stack = data.stack.clone();
+		this.stack = data.stack != null ? data.stack.clone() : null;
 		this.type = data.type;
 		this.blockValues = data.blockValues;
 		this.isAlias = data.isAlias;
 		this.plain = data.plain;
 		this.itemFlags = data.itemFlags;
 	}
+
+	public ItemData(Material material, @Nullable BlockValues values) {
+		this.type = material;
+		this.blockValues = values;
+	}
 	
 	public ItemData(ItemStack stack, @Nullable BlockValues values) {
 		this.stack = stack;
@@ -200,7 +206,8 @@ public ItemData(BlockState blockState) {
 
 	public ItemData(BlockData blockData) {
 		this.type = blockData.getMaterial();
-		this.stack = new ItemStack(type);
+		if (type.isItem())
+			this.stack = new ItemStack(type);
 		this.blockValues = BlockCompat.INSTANCE.getBlockValues(blockData);
 	}
 	
@@ -227,13 +234,12 @@ public boolean isOfType(@Nullable ItemStack item) {
 		if (type != item.getType())
 			return false; // Obvious mismatch
 		
-		if (itemFlags != 0) { // Either stack has tags (or durability)
+		if (stack != null && itemFlags != 0) { // Either stack has tags (or durability)
 			if (ItemUtils.getDamage(stack) != ItemUtils.getDamage(item))
 				return false; // On 1.12 and below, damage is not in meta
 			if (stack.hasItemMeta() == item.hasItemMeta()) // Compare ItemMeta as in isSimilar() of ItemStack
-				return stack.hasItemMeta() ? itemFactory.equals(stack.getItemMeta(), item.getItemMeta()) : true;
-			else
-				return false;
+				return !stack.hasItemMeta() || itemFactory.equals(stack.getItemMeta(), item.getItemMeta());
+			return false;
 		}
 		return true;
 	}
@@ -249,7 +255,7 @@ public String toString() {
 	
 	public String toString(final boolean debug, final boolean plural) {
 		StringBuilder builder = new StringBuilder(Aliases.getMaterialName(this, plural));
-		ItemMeta meta = stack.getItemMeta();
+		ItemMeta meta = stack != null ? stack.getItemMeta() : null;
 		if (meta != null && meta.hasDisplayName()) {
 			builder.append(" ").append(m_named).append(" ");
 			builder.append(meta.getDisplayName());
@@ -282,7 +288,7 @@ public boolean equals(final @Nullable Object obj) {
 	@Override
 	public int hashCode() {
 		int hash = type.hashCode(); // Has collisions, but probably not too many of them
-		if (blockValues == null || (blockValues != null && blockValues.isDefault())) {
+		if (blockValues == null || blockValues.isDefault()) {
 			hash = hash * 37 + 1;
 		}
 		return hash;
@@ -351,7 +357,7 @@ public MatchQuality matchAlias(ItemData item) {
 		}
 		
 		// See if we need to compare item metas (excluding durability)
-		if (quality.isAtLeast(MatchQuality.SAME_ITEM) && stack.hasItemMeta() || item.stack.hasItemMeta()) { // Item meta checks could lower this
+		if (quality.isAtLeast(MatchQuality.SAME_ITEM) && this.hasItemMeta() || item.hasItemMeta()) { // Item meta checks could lower this
 			MatchQuality metaQuality = compareItemMetas(getItemMeta(), item.getItemMeta());
 			
 			// If given item doesn't care about meta, promote to SAME_ITEM
@@ -489,9 +495,13 @@ public ItemData intersection(final ItemData other) {
 	 * It is not a copy, so please be careful.
 	 * @return Item stack.
 	 */
-	public ItemStack getStack() {
+	public @Nullable ItemStack getStack() {
 		return stack;
 	}
+
+	private boolean hasItemMeta() {
+		return stack != null && stack.hasItemMeta();
+	}
 	
 	@Override
 	public ItemData clone() {
@@ -508,7 +518,7 @@ public BlockValues getBlockValues() {
 	}
 	
 	public ItemMeta getItemMeta() {
-		ItemMeta meta = stack.getItemMeta();
+		ItemMeta meta = stack != null ? stack.getItemMeta() : null;
 		if (meta == null) { // AIR has null item meta!
 			meta = itemFactory.getItemMeta(Material.STONE);
 		}
@@ -517,6 +527,8 @@ public ItemMeta getItemMeta() {
 	}
 	
 	public void setItemMeta(ItemMeta meta) {
+		if (stack == null)
+			return;
 		stack.setItemMeta(meta);
 		isAlias = false; // This is no longer exact alias
 		plain = false; // This is no longer a plain item
@@ -524,10 +536,14 @@ public void setItemMeta(ItemMeta meta) {
 	}
 	
 	public int getDurability() {
+		if (stack == null)
+			return 0; // no damage?
 		return ItemUtils.getDamage(stack);
 	}
 	
 	public void setDurability(int durability) {
+		if (stack == null)
+			return;
 		ItemUtils.setDamage(stack, durability);
 		isAlias = false; // Change happened
 		plain = false; // This is no longer a plain item
@@ -567,7 +583,7 @@ public boolean matchPlain(ItemData other) {
 	public Fields serialize() throws NotSerializableException {
 		Fields fields = new Fields(this); // ItemStack is transient, will be ignored
 		fields.putPrimitive("id", type.ordinal());
-		fields.putObject("meta", stack.getItemMeta());
+		fields.putObject("meta", stack != null ? stack.getItemMeta() : null);
 		return fields;
 	}
 
@@ -579,8 +595,10 @@ public void deserialize(Fields fields) throws StreamCorruptedException, NotSeria
 		ItemMeta meta = fields.getAndRemoveObject("meta", ItemMeta.class);
 
 		// Initialize ItemStack
-		this.stack = new ItemStack(type);
-		stack.setItemMeta(meta); // Just set meta to it
+		if (meta != null && type.isItem()) {
+			this.stack = new ItemStack(type);
+			stack.setItemMeta(meta); // Just set meta to it
+		}
 
 		fields.setFields(this); // Everything but ItemStack and Material
 	}
@@ -598,17 +616,17 @@ public void deserialize(Fields fields) throws StreamCorruptedException, NotSeria
 	 */
 	public ItemData aliasCopy() {
 		ItemData data = new ItemData();
-		data.stack = new ItemStack(type, 1);
-		
-		if (stack.hasItemMeta()) {
-			ItemMeta meta = stack.getItemMeta(); // Creates a copy
-			meta.setDisplayName(null); // Clear display name
-			if (!itemFactory.getItemMeta(type).equals(meta)) // there may be different tags (e.g. potions)
-				data.itemFlags |= ItemFlags.CHANGED_TAGS;
-			data.stack.setItemMeta(meta);
+		if (stack != null) {
+			data.stack = new ItemStack(type, 1);
+			if (stack.hasItemMeta()) {
+				ItemMeta meta = stack.getItemMeta(); // Creates a copy
+				meta.setDisplayName(null); // Clear display name
+				if (!itemFactory.getItemMeta(type).equals(meta)) // there may be different tags (e.g. potions)
+					data.itemFlags |= ItemFlags.CHANGED_TAGS;
+				data.stack.setItemMeta(meta);
+			}
+			ItemUtils.setDamage(data.stack, 0); // Set to undamaged
 		}
-		ItemUtils.setDamage(data.stack, 0); // Set to undamaged
-
 		data.type = type;
 		data.blockValues = blockValues;
 		data.itemForm = itemForm;
@@ -620,6 +638,8 @@ public ItemData aliasCopy() {
 	 * @param tags Tags in Mojang's JSON format.
 	 */
 	public void applyTags(String tags) {
+		if (stack == null)
+			return;
 		BukkitUnsafe.modifyItemStack(stack, tags);
 		itemFlags |= ItemFlags.CHANGED_TAGS;
 	}
diff --git a/src/main/java/ch/njol/skript/aliases/ItemType.java b/src/main/java/ch/njol/skript/aliases/ItemType.java
index 7341667fa91..0b47617ef5c 100644
--- a/src/main/java/ch/njol/skript/aliases/ItemType.java
+++ b/src/main/java/ch/njol/skript/aliases/ItemType.java
@@ -68,6 +68,7 @@
 import java.util.Random;
 import java.util.RandomAccess;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 @ContainerType(ItemStack.class)
 public class ItemType implements Unit, Iterable<ItemData>, Container<ItemStack>, YggdrasilExtendedSerializable {
@@ -315,7 +316,7 @@ public boolean isOfType(Material id, @Nullable String tags) {
 
 	public boolean isOfType(Material id) {
 		// TODO avoid object creation
-		return isOfType(new ItemData(id, null));
+		return isOfType(new ItemData(id, (String) null));
 	}
 
 	/**
@@ -343,7 +344,7 @@ public ItemType getBlock() {
 	 */
 	public boolean hasItem() {
 		for (ItemData d : types) {
-			if (!d.type.isBlock())
+			if (d.type.isItem())
 				return true;
 		}
 		return false;
@@ -487,9 +488,13 @@ public boolean hasNext() {
 
 			@Override
 			public ItemStack next() {
-				if (!hasNext())
-					throw new NoSuchElementException();
-				ItemStack is = iter.next().getStack().clone();
+				ItemStack is = null;
+				while (is == null) {
+					if (!hasNext())
+						throw new NoSuchElementException();
+					is = iter.next().getStack();
+				}
+				is = is.clone();
 				is.setAmount(getAmount());
 				return is;
 			}
@@ -588,10 +593,17 @@ public ItemType clone() {
 	 * @see #removeFrom(ItemStack)
 	 * @see #removeFrom(List...)
 	 */
-	public ItemStack getRandom() {
-		int numItems = types.size();
+	public @Nullable ItemStack getRandom() {
+		List<ItemData> datas = types.stream()
+				.filter(data -> data.stack != null)
+				.collect(Collectors.toList());
+		if (datas.isEmpty())
+			return null;
+		int numItems = datas.size();
 		int index = random.nextInt(numItems);
-		ItemStack is = types.get(index).getStack().clone();
+		ItemStack is = datas.get(index).getStack();
+		assert is != null; // verified above
+		is = is.clone();
 		is.setAmount(getAmount());
 		return is;
 	}
@@ -869,7 +881,9 @@ public final boolean removeFrom(boolean replaceWithNull, List<ItemStack>... list
 	 */
 	public void addTo(final List<ItemStack> list) {
 		if (!isAll()) {
-			list.add(getItem().getRandom());
+			ItemStack random = getItem().getRandom();
+			if (random != null)
+				list.add(getItem().getRandom());
 			return;
 		}
 		for (final ItemStack is : getItem().getAll())
@@ -936,7 +950,9 @@ private static boolean addTo(@Nullable ItemStack is, ItemStack[] buf) {
 
 	public boolean addTo(final ItemStack[] buf) {
 		if (!isAll()) {
-			return addTo(getItem().getRandom(), buf);
+			ItemStack random = getItem().getRandom();
+			if (random != null)
+				return addTo(getItem().getRandom(), buf);
 		}
 		boolean ok = true;
 		for (ItemStack is : getItem().getAll()) {
diff --git a/src/main/java/ch/njol/skript/bukkitutil/HealthUtils.java b/src/main/java/ch/njol/skript/bukkitutil/HealthUtils.java
index 20b5120a0f1..be8675ccabb 100644
--- a/src/main/java/ch/njol/skript/bukkitutil/HealthUtils.java
+++ b/src/main/java/ch/njol/skript/bukkitutil/HealthUtils.java
@@ -26,13 +26,13 @@
 import org.bukkit.damage.DamageSource;
 import org.bukkit.damage.DamageType;
 import org.bukkit.entity.Damageable;
+import org.bukkit.entity.LivingEntity;
 import org.bukkit.event.entity.EntityDamageEvent;
 import org.bukkit.event.entity.EntityDamageEvent.DamageCause;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 
 public class HealthUtils {
 
@@ -112,8 +112,11 @@ public static double getFinalDamage(EntityDamageEvent e) {
 		return e.getFinalDamage() / 2;
 	}
 	
-	public static void setDamage(EntityDamageEvent e, double damage) {
-		e.setDamage(damage * 2);
+	public static void setDamage(EntityDamageEvent event, double damage) {
+		event.setDamage(damage * 2);
+		// Set last damage manually as Bukkit doesn't appear to do that
+		if (event.getEntity() instanceof LivingEntity)
+			((LivingEntity) event.getEntity()).setLastDamage(damage * 2);
 	}
 
 	@Nullable
diff --git a/src/main/java/ch/njol/skript/bukkitutil/ItemUtils.java b/src/main/java/ch/njol/skript/bukkitutil/ItemUtils.java
index 31bf99c2d56..216be44b918 100644
--- a/src/main/java/ch/njol/skript/bukkitutil/ItemUtils.java
+++ b/src/main/java/ch/njol/skript/bukkitutil/ItemUtils.java
@@ -42,9 +42,17 @@ public class ItemUtils {
 	 * @return Damage.
 	 */
 	public static int getDamage(ItemStack itemStack) {
-		ItemMeta meta = itemStack.getItemMeta();
-		if (meta instanceof Damageable)
-			return ((Damageable) meta).getDamage();
+		return getDamage(itemStack.getItemMeta());
+	}
+
+	/**
+	 * Gets damage/durability of an itemmeta, or 0 if it does not have damage.
+	 * @param itemMeta ItemMeta.
+	 * @return Damage.
+	 */
+	public static int getDamage(ItemMeta itemMeta) {
+		if (itemMeta instanceof Damageable)
+			return ((Damageable) itemMeta).getDamage();
 		return 0; // Non damageable item
 	}
 
@@ -143,15 +151,22 @@ public static Material asItem(Material type) {
 	/**
 	 * Tests whether two item stacks are of the same type, i.e. it ignores the amounts.
 	 *
-	 * @param is1
-	 * @param is2
+	 * @param itemStack1
+	 * @param itemStack2
 	 * @return Whether the item stacks are of the same type
 	 */
-	public static boolean itemStacksEqual(final @Nullable ItemStack is1, final @Nullable ItemStack is2) {
-		if (is1 == null || is2 == null)
-			return is1 == is2;
-		return is1.getType() == is2.getType() && ItemUtils.getDamage(is1) == ItemUtils.getDamage(is2)
-			&& is1.getItemMeta().equals(is2.getItemMeta());
+	public static boolean itemStacksEqual(@Nullable ItemStack itemStack1, @Nullable ItemStack itemStack2) {
+		if (itemStack1 == null || itemStack2 == null)
+			return itemStack1 == itemStack2;
+		if (itemStack1.getType() != itemStack2.getType())
+			return false;
+
+		ItemMeta itemMeta1 = itemStack1.getItemMeta();
+		ItemMeta itemMeta2 = itemStack2.getItemMeta();
+		if (itemMeta1 == null || itemMeta2 == null)
+			return itemMeta1 == itemMeta2;
+
+		return itemStack1.getItemMeta().equals(itemStack2.getItemMeta());
 	}
 
 	// Only 1.15 and versions after have Material#isAir method
diff --git a/src/main/java/ch/njol/skript/bukkitutil/block/BlockCompat.java b/src/main/java/ch/njol/skript/bukkitutil/block/BlockCompat.java
index eef0866a01b..87bc45a6ec8 100644
--- a/src/main/java/ch/njol/skript/bukkitutil/block/BlockCompat.java
+++ b/src/main/java/ch/njol/skript/bukkitutil/block/BlockCompat.java
@@ -65,6 +65,9 @@ default BlockValues getBlockValues(Block block) {
 		return getBlockValues(block.getBlockData());
 	}
 
+	@Nullable
+	BlockValues getBlockValues(Material material);
+
 	@Nullable
 	BlockValues getBlockValues(BlockData blockData);
 	
diff --git a/src/main/java/ch/njol/skript/bukkitutil/block/NewBlockCompat.java b/src/main/java/ch/njol/skript/bukkitutil/block/NewBlockCompat.java
index 2a0ecd36da8..e5cf9c0567b 100644
--- a/src/main/java/ch/njol/skript/bukkitutil/block/NewBlockCompat.java
+++ b/src/main/java/ch/njol/skript/bukkitutil/block/NewBlockCompat.java
@@ -336,6 +336,13 @@ public BlockValues getBlockValues(BlockState blockState) {
 		return getBlockValues(blockState.getBlockData());
 	}
 
+	@Override
+	public @Nullable BlockValues getBlockValues(Material material) {
+		if (material.isBlock())
+			return new NewBlockValues(material, Bukkit.createBlockData(material), false);
+		return null;
+	}
+
 	@Nullable
 	@Override
 	public BlockValues getBlockValues(BlockData blockData) {
diff --git a/src/main/java/ch/njol/skript/classes/data/BukkitClasses.java b/src/main/java/ch/njol/skript/classes/data/BukkitClasses.java
index 530c3df07a5..a54e5a54cc4 100644
--- a/src/main/java/ch/njol/skript/classes/data/BukkitClasses.java
+++ b/src/main/java/ch/njol/skript/classes/data/BukkitClasses.java
@@ -933,6 +933,7 @@ public String toVariableNameString(InventoryHolder holder) {
 				.since("1.0")
 				.after("number")
 				.supplier(() -> Arrays.stream(Material.values())
+					.filter(Material::isItem)
 					.map(ItemStack::new)
 					.iterator())
 				.parser(new Parser<ItemStack>() {
diff --git a/src/main/java/ch/njol/skript/classes/data/DefaultConverters.java b/src/main/java/ch/njol/skript/classes/data/DefaultConverters.java
index 00f419f4901..a90de6957d3 100644
--- a/src/main/java/ch/njol/skript/classes/data/DefaultConverters.java
+++ b/src/main/java/ch/njol/skript/classes/data/DefaultConverters.java
@@ -176,6 +176,14 @@ public DefaultConverters() {}
 				return ((Block) holder).getLocation();
 			if (holder instanceof BlockState)
 				return BlockUtils.getLocation(((BlockState) holder).getBlock());
+			if (holder instanceof DoubleChest) {
+				DoubleChest doubleChest = (DoubleChest) holder;
+				if (doubleChest.getLeftSide() != null) {
+					return BlockUtils.getLocation(((BlockState) doubleChest.getLeftSide()).getBlock());
+				} else if (((DoubleChest) holder).getRightSide() != null) {
+					return BlockUtils.getLocation(((BlockState) doubleChest.getRightSide()).getBlock());
+				}
+			}
 			return null;
 		});
 
diff --git a/src/main/java/ch/njol/skript/effects/EffTeleport.java b/src/main/java/ch/njol/skript/effects/EffTeleport.java
index 3ba06d7d150..990e1aa7ec1 100644
--- a/src/main/java/ch/njol/skript/effects/EffTeleport.java
+++ b/src/main/java/ch/njol/skript/effects/EffTeleport.java
@@ -19,7 +19,6 @@
 package ch.njol.skript.effects;
 
 import ch.njol.skript.Skript;
-import ch.njol.skript.sections.EffSecSpawn;
 import ch.njol.skript.sections.EffSecSpawn.SpawnEvent;
 import ch.njol.skript.bukkitutil.EntityUtils;
 import ch.njol.skript.doc.Description;
@@ -31,7 +30,6 @@
 import ch.njol.skript.lang.SkriptParser.ParseResult;
 import ch.njol.skript.lang.Trigger;
 import ch.njol.skript.lang.TriggerItem;
-import ch.njol.skript.lang.TriggerSection;
 import ch.njol.skript.timings.SkriptTimings;
 import ch.njol.skript.util.Direction;
 import ch.njol.skript.variables.Variables;
@@ -53,7 +51,7 @@
 	"which may cause lag spikes or server crashes when using this effect to teleport entities to unloaded chunks."
 })
 @Examples({
-	"teleport the player to {homes.%player%}",
+	"teleport the player to {homes::%player%}",
 	"teleport the attacker to the victim"
 })
 @Since("1.0")
@@ -101,6 +99,7 @@ protected TriggerItem walk(Event e) {
 		Location loc = location.getSingle(e);
 		if (loc == null)
 			return next;
+		boolean unknownWorld = !loc.isWorldLoaded();
 
 		Entity[] entityArray = entities.getArray(e); // We have to fetch this before possible async execution to avoid async local variable access.
 		if (entityArray.length == 0)
@@ -108,11 +107,17 @@ protected TriggerItem walk(Event e) {
 
 		if (!delayed) {
 			if (e instanceof PlayerRespawnEvent && entityArray.length == 1 && entityArray[0].equals(((PlayerRespawnEvent) e).getPlayer())) {
+				if (unknownWorld)
+					return next;
 				((PlayerRespawnEvent) e).setRespawnLocation(loc);
 				return next;
 			}
 
 			if (e instanceof PlayerMoveEvent && entityArray.length == 1 && entityArray[0].equals(((PlayerMoveEvent) e).getPlayer())) {
+				if (unknownWorld) { // we can approximate the world
+					loc = loc.clone();
+					loc.setWorld(((PlayerMoveEvent) e).getFrom().getWorld());
+				}
 				((PlayerMoveEvent) e).setTo(loc);
 				return next;
 			}
@@ -125,6 +130,19 @@ protected TriggerItem walk(Event e) {
 			return next;
 		}
 
+		if (unknownWorld) { // we can't fetch the chunk without a world
+			if (entityArray.length == 1) { // if there's 1 thing we can borrow its world
+				Entity entity = entityArray[0];
+				if (entity == null)
+					return next;
+				// assume it's a local teleport, use the first entity we find as a reference
+				loc = loc.clone();
+				loc.setWorld(entity.getWorld());
+			} else {
+				return next; // no entities = no chunk = nobody teleporting
+			}
+		}
+		final Location fixed = loc;
 		Delay.addDelayedEvent(e);
 		Object localVars = Variables.removeLocals(e);
 		
@@ -132,7 +150,7 @@ protected TriggerItem walk(Event e) {
 		PaperLib.getChunkAtAsync(loc).thenAccept(chunk -> {
 			// The following is now on the main thread
 			for (Entity entity : entityArray) {
-				EntityUtils.teleport(entity, loc);
+				EntityUtils.teleport(entity, fixed);
 			}
 
 			// Re-set local variables
diff --git a/src/main/java/ch/njol/skript/expressions/ExprLastDamage.java b/src/main/java/ch/njol/skript/expressions/ExprLastDamage.java
index 0b62cd60a9d..ede427b156f 100644
--- a/src/main/java/ch/njol/skript/expressions/ExprLastDamage.java
+++ b/src/main/java/ch/njol/skript/expressions/ExprLastDamage.java
@@ -19,47 +19,34 @@
  */
 package ch.njol.skript.expressions;
 
-import org.bukkit.entity.LivingEntity;
-import org.bukkit.event.Event;
-import org.eclipse.jdt.annotation.Nullable;
-
 import ch.njol.skript.classes.Changer.ChangeMode;
 import ch.njol.skript.doc.Description;
 import ch.njol.skript.doc.Examples;
 import ch.njol.skript.doc.Name;
 import ch.njol.skript.doc.Since;
 import ch.njol.skript.expressions.base.SimplePropertyExpression;
-import ch.njol.skript.lang.Expression;
-import ch.njol.skript.lang.SkriptParser;
-import ch.njol.util.Kleenean;
 import ch.njol.util.coll.CollectionUtils;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.Nullable;
 
 @Name("Last Damage")
 @Description("The last damage that was done to an entity. Note that changing it doesn't deal more/less damage.")
 @Examples({"set last damage of event-entity to 2"})
 @Since("2.5.1")
 public class ExprLastDamage extends SimplePropertyExpression<LivingEntity, Number> {
-	
+
 	static {
 		register(ExprLastDamage.class, Number.class, "last damage", "livingentities");
 	}
-	
-	@Nullable
-	private ExprDamage damageExpr;
-	
-	@Override
-	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, SkriptParser.ParseResult parseResult) {
-		damageExpr = new ExprDamage();
-		return true;
-	}
-	
+
 	@Nullable
 	@Override
 	@SuppressWarnings("null")
 	public Number convert(LivingEntity livingEntity) {
-		return damageExpr.get(livingEntity.getLastDamageCause())[0];
+		return livingEntity.getLastDamage() / 2;
 	}
-	
+
 	@Nullable
 	@Override
 	public Class<?>[] acceptChange(ChangeMode mode) {
@@ -72,35 +59,38 @@ public Class<?>[] acceptChange(ChangeMode mode) {
 				return null;
 		}
 	}
-	
+
+	@SuppressWarnings("ConstantValue")
 	@Override
 	public void change(Event e, @Nullable Object[] delta, ChangeMode mode) {
-		if (delta != null) {
+		if (delta != null && delta[0] instanceof Number) {
+			double damage = ((Number) delta[0]).doubleValue() * 2;
+
 			switch (mode) {
 				case SET:
 					for (LivingEntity entity : getExpr().getArray(e))
-						entity.setLastDamage((Long) delta[0]);
+						entity.setLastDamage(damage);
 					break;
 				case REMOVE:
-					delta[0] = (Long) delta[0] * -1;
+					damage = damage * -1;
 				case ADD:
 					for (LivingEntity entity : getExpr().getArray(e))
-						entity.setLastDamage((Long) delta[0] + entity.getLastDamage());
+						entity.setLastDamage(damage + entity.getLastDamage());
 					break;
 				default:
 					assert false;
 			}
 		}
 	}
-	
+
 	@Override
 	public Class<? extends Number> getReturnType() {
 		return Number.class;
 	}
-	
+
 	@Override
 	protected String getPropertyName() {
 		return "last damage";
 	}
-	
+
 }
diff --git a/src/test/skript/environments/java21/paper-1.21.0.json b/src/test/skript/environments/java21/paper-1.21.0.json
new file mode 100644
index 00000000000..22a72e3a73b
--- /dev/null
+++ b/src/test/skript/environments/java21/paper-1.21.0.json
@@ -0,0 +1,17 @@
+{
+	"name": "paper-1.21.0",
+	"resources": [
+		{"source": "server.properties.generic", "target": "server.properties"}
+	],
+	"paperDownloads": [
+		{
+			"version": "1.21",
+			"target": "paperclip.jar"
+		}
+	],
+	"skriptTarget": "plugins/Skript.jar",
+	"commandLine": [
+		"-Dcom.mojang.eula.agree=true",
+		"-jar", "paperclip.jar", "--nogui"
+	]
+}
diff --git a/src/test/skript/tests/regressions/5491-xp orb merge overwrite.sk b/src/test/skript/tests/regressions/5491-xp orb merge overwrite.sk
index ca5b9b46d6e..c925f51c590 100644
--- a/src/test/skript/tests/regressions/5491-xp orb merge overwrite.sk	
+++ b/src/test/skript/tests/regressions/5491-xp orb merge overwrite.sk	
@@ -1,6 +1,10 @@
 test "spawn xp orb overwriting merged value" when running minecraft "1.14.4":
 	# 1.13.2 seems not to merge xp orbs in the same way, so this test is skipped
 
+	# 1.21 also does not merge orbs, so this test is disabled.
+	# TODO: figure out how to force the orbs to merge on 1.21+
+	running below minecraft "1.21"
+
 	# sanitize
 	kill all xp orbs
 	set {_spawn} to spawn of world "world"
diff --git a/src/test/skript/tests/regressions/6811-inventory-holder-location-doublechest.sk b/src/test/skript/tests/regressions/6811-inventory-holder-location-doublechest.sk
new file mode 100644
index 00000000000..f46d4b52794
--- /dev/null
+++ b/src/test/skript/tests/regressions/6811-inventory-holder-location-doublechest.sk
@@ -0,0 +1,20 @@
+test "inventory holder location double chest":
+	set {_b::1} to the block at spawn of world "world"
+	set {_b::2} to the block north of {_b::1}
+	set {_prev::1} to type of block at {_b::1}
+	set {_prev::2} to type of block at {_b::2}
+
+	set block at {_b::1} to chest[facing=east;type=right]
+	set block at {_b::2} to chest[facing=east;type=left]
+
+	set {_inv} to inventory of {_b::1}
+	set {_holder} to holder of {_inv}
+
+	set {_a-loc} to location of {_holder}
+	set {_b-loc::*} to location of {_b::1} and location of {_b::2}
+
+	# clean up first in case assert fails
+	set block at {_b::1} to {_prev::1}
+	set block at {_b::2} to {_prev::2}
+
+	assert {_b-loc::*} contains {_a-loc} with "holder location of double chest differs from block location"
diff --git a/src/test/skript/tests/regressions/6830-remove air from slot.sk b/src/test/skript/tests/regressions/6830-remove air from slot.sk
new file mode 100644
index 00000000000..13eaa29b1d3
--- /dev/null
+++ b/src/test/skript/tests/regressions/6830-remove air from slot.sk	
@@ -0,0 +1,4 @@
+test "remove air from air slot":
+	set {_chest} to chest inventory with 3 rows
+	# throws exception if not fixed
+	remove 1 of (slot 0 of {_chest}) from (slot 0 of {_chest})
diff --git a/src/test/skript/tests/syntaxes/effects/EffGlowingText.sk b/src/test/skript/tests/syntaxes/effects/EffGlowingText.sk
index b43a5786755..d39b3e6988a 100644
--- a/src/test/skript/tests/syntaxes/effects/EffGlowingText.sk
+++ b/src/test/skript/tests/syntaxes/effects/EffGlowingText.sk
@@ -10,7 +10,7 @@ test "glowing sign blocks" when running minecraft "1.17.1":
 	set block at {_loc} to {_original block}
 
 test "glowing sign items" when running minecraft "1.17.1":
-	set {_sign} to sign
+	set {_sign} to floor sign
 	assert {_sign} doesn't have glowing text with "Sign had glowing text erroneously (1)"
 	make {_sign} have glowing text
 	assert {_sign} has glowing text with "Sign had normal text erroneously"
diff --git a/src/test/skript/tests/syntaxes/expressions/ExprAmountOfItems.sk b/src/test/skript/tests/syntaxes/expressions/ExprAmountOfItems.sk
new file mode 100644
index 00000000000..9e40ff707ca
--- /dev/null
+++ b/src/test/skript/tests/syntaxes/expressions/ExprAmountOfItems.sk
@@ -0,0 +1,14 @@
+test "amount of items":
+	set {_inventory} to a hopper inventory named "test"
+	assert the amount of stone in {_inventory} is 0 with "default amount failed"
+	add stone to {_inventory}
+	assert the amount of stone in {_inventory} is 1 with "single amount failed"
+	add stone named "bread" to {_inventory}
+	assert the amount of stone in {_inventory} is 2 with "different named items amount failed"
+	add 100 of iron ingot to {_inventory}
+	assert the amount of stone in {_inventory} is 2 with "add different item amount failed"
+	assert the amount of iron ingot in {_inventory} is 100 with "add 100 item amount failed"
+	remove stone from {_inventory}
+	assert the amount of stone in {_inventory} is 1 with "removed one amount failed"
+	remove stone from {_inventory}
+	assert the amount of stone in {_inventory} is 0 with "removed all amount failed"
diff --git a/src/test/skript/tests/syntaxes/expressions/ExprItemWithCustomModelData.sk b/src/test/skript/tests/syntaxes/expressions/ExprItemWithCustomModelData.sk
new file mode 100644
index 00000000000..098cda9abee
--- /dev/null
+++ b/src/test/skript/tests/syntaxes/expressions/ExprItemWithCustomModelData.sk
@@ -0,0 +1,13 @@
+test "item with custom model data" when minecraft version is not "1.13.2":
+	set {_i} to stone
+	assert the custom model data of {_i} is 0 with "default model data failed"
+	set {_i} to stone with custom model data 5
+	assert the custom model data of {_i} is 5 with "simple model data set failed"
+	set {_i} to stone with custom model data -1
+	assert the custom model data of {_i} is -1 with "negative model data set failed"
+	set {_i} to {_i} with custom model data 2
+	assert the custom model data of {_i} is 2 with "existing item model data set failed"
+	set {_i} to {_i} with custom model data 3.3
+	assert the custom model data of {_i} is 3 with "decimal item model data set failed"
+	set {_i} to {_i} with custom model data 3.999
+	assert the custom model data of {_i} is 3 with "close decimal item model data set failed"
diff --git a/src/test/skript/tests/syntaxes/expressions/ExprItemsIn.sk b/src/test/skript/tests/syntaxes/expressions/ExprItemsIn.sk
index b5ef324b555..ce5253d40b0 100644
--- a/src/test/skript/tests/syntaxes/expressions/ExprItemsIn.sk
+++ b/src/test/skript/tests/syntaxes/expressions/ExprItemsIn.sk
@@ -1,3 +1,29 @@
+
+test "items in (inventory)":
+	set {_inventory} to a hopper inventory named "test"
+	add stone to {_inventory}
+	add stone named "bread" to {_inventory}
+	add 100 of iron ingot to {_inventory}
+	loop items in {_inventory}:
+		if loop-value is stone:
+			continue
+		else if loop-value is iron ingot:
+			continue
+		else:
+			assert true is false with "unexpected item in the inventory area: %loop-value%"
+	set {_list::*} to items in {_inventory}
+	assert size of {_list::*} is 4 with "size of items in failed"
+	assert {_list::1} is stone with "first item failed"
+	assert {_list::2} is stone named "bread" with "second item failed"
+	assert {_list::3} is 64 of iron ingot with "third item failed"
+	assert {_list::4} is 36 of iron ingot with "split fourth item failed"
+	remove stone from {_inventory}
+	set {_list::*} to items in {_inventory}
+	assert size of {_list::*} is 3 with "size of second items in failed"
+	assert {_list::1} is stone named "bread" with "new first item failed"
+	assert {_list::2} is 64 of iron ingot with "new second item failed"
+	assert {_list::3} is 36 of iron ingot with "new third item failed"
+
 test "filtering ExprItemsIn":
 	set {_world} to random world out of all worlds
 	set block at spawn of {_world} to chest
diff --git a/src/test/skript/tests/syntaxes/expressions/ExprLastDamage.sk b/src/test/skript/tests/syntaxes/expressions/ExprLastDamage.sk
new file mode 100644
index 00000000000..0ed3f3f3e4c
--- /dev/null
+++ b/src/test/skript/tests/syntaxes/expressions/ExprLastDamage.sk
@@ -0,0 +1,15 @@
+test "last damage":
+	set {_l} to location 0.5 above highest block at location(1,1,1)
+	spawn a sheep at {_l}
+	set {_e} to last spawned entity
+
+	assert last damage of {_e} = 0 with "last damage of newly spawned entity should be 0"
+
+	damage {_e} by 1
+	assert last damage of {_e} = 1 with "last damage of entity should be 1 after damaging it by 1"
+
+	set last damage of {_e} to 3
+	assert last damage of {_e} = 3 with "last damage of entity should be 3 after setting to 3"
+
+	# thank you for your service
+	delete entity in {_e}