Lich

Lich is a type of unique boss monster. There are three Liches: two Abyssal Liches and one found in Delve.

All of these monsters have a chance to drop unique items that have Abyssal Socket(s). Additionally, Kurgal has a chance to drop, or  instead.

In terms of Challenges, "Lich" exclusively refers to the two Abyssal Liches.