His reanimation is the goal of a warlock quest to gain the ability to summon infernals.
Considering you are given the quest to defeat Kroshius at level 50 but the mob in question is actually 55, great care must be taken if you are trying to complete it solo. The biggest hurdle to a level 50 player attempting this feat is the level difference lowering your spell hit rating, so many players will prefer to wait before attempting. Despite being an infernal, Kroshius is susceptible to fear, fire damage and enslavement, all of which you can use to your advantage. One effective strategy is to:
- Distract Kroshius with a Voidwalker
- Cast Curse of Shadow on Kroshius
- Enslave Kroshius
- Use Kroshius against an Entropic Horror or another infernal in the area
It is still possible for Kroshius to break free early, leaving both mobs for you to contend.
Since infernals are usually summoned, and have rarely displayed sentience and rarely show signs of personality, it's odd that an infernal would have a name and be acting independently. However, Kroshius is not unique in this - the infernal Raze, while under the control of a human by the name of Nilith Lokrav, also is sentient and speaks, showing a similar simplistic "smash!" worldview as Kroshius.
- Patch 1.4.0 (2005-05-05): Added.