Summoner (Hib)  

This guy is DEADLY at lower levels. Despite only being level 5, he can own me when he's blue.

He doesn't physically attack you, he instead insta casts an ice spell that does around 10-14 damage per cast, and he can chain cast it a lot of times. He also casts a disease spell that lowers your constitution. If you pull him at long range, he'll stop and cast a poison spell on you.