A Black Sludge is a held item that heals Poison-type Pokémon by 1 of their maximum HP every turn. If the holder is not a Poison-type Pokémon, it will lose 1 of its maximum HP every turn instead. It can be obtained as a tier 2 special drop. It is also a drop from certain wild Pokémon.
Before Reforged, this item had the following recipe. It was removed due to many held items being far too easy to make.