DIABLO(I,II,III)

permanent ban for a specific difficulty level. but, we're talking about Hell, aren't we?

Necromancers and Sorceresses (except for Light ones) can accidentally kill the King of the Minotaurs with their spells, which results in a permanent closure of the cow level, so Fury and Trapper are the best choices in this regard, and a Light Sorceress can also work.

If you want to be precise, anyone can "accidentally" kill him. Especially with uncontrolled traps. However, I personally never touched the King or the Minotaurs close to him if I planned to continue running the cow level.
Among different characters, only the speed of clearing the cow level as a whole matters, which is especially high for Trapper and Fury. It's all quite simple.