Doom Items

These items possess strange abilities, both when right clicked or left clicked, they will do something. However they do require a fuel, that the player has to have in his off hand. Note that left click abilities do not consume fuel.

They are drop-only and can only be obtain by slaying the monster using them.

They can be infused with Supreme Enchant Books, and they will retain both the new enchantments and their abilities. They can even be infused with Wither Items, and will retain some of their enchantments, however they will not gain the abilities of that wither item and the wither item will be destroyed in the process, so do this at your own risk.

Placing or Changing Spawners
Spawners are bound by world, so the player won't be able to place spawners where the entity wouldn't normally spawn. This also applies to the use of eggs in order to change a spawner's entity.

Egg Collection Exceptions
Not all mobs can be turned into eggs, and it will only work on monsters, meaning that it doesn't work with animals or villagers. Those exceptions are Endermite, Silverfish, Ender Dragon, Wither and Shulkers.

Note that not even Syntetic Shulker Eggs will work in spanwers.