Wulfrum Slime

The Wulfrum Slime is a Pre-Hardmode slime which does not spawn naturally. It is immune to knockback, making it potentially troublesome to fight for early players. It drops Wulfrum Metal Scraps, which are a valuable early-game crafting material used to craft various wulfrum items.

As it does not spawn naturally, the only way of it existing in a world is through manual spawn options from other mods. (e.g. Cheat Sheet)