Packet corresponds to this client function call:
/**
* This function is called when the server indicates that an entity has left
* the player's AoI. It is complicated because it may be called out of order.
*
* @param id entity id.
* @param cacheStamps Unused parameter.
*/
void EntityManager::onEntityLeave( EntityID id, const CacheStamps & cacheStamps )
And here how it looks like:
struct EntityLeave {
int32 entityID;
}