Setag is one of the first quest bosses in the game, for the quest Kill Setag.
Setag deals 48-54 (+25) magic damage at 600 range, has 0(+8) points of light armor and has 925 base HP plus 300 from equipment. Statwise he has an underwhelming 33 Strength, 24 Agility and 46+20 Intelligence. His abilities are Auto-Life, Haste, Armor Break, Shell, Regen, and Poison (from item).
The most dangerous part about this engagement are probably the three Abomination he starts out with as well as the three Abominations that spawn for a total of six. Together with his arsenal of spells he can be quite annoying but his HP are so menial that it is possible to nuke him fairly easily fairly early on. Although Halaster the archwizard will help you out he doesn't seem to do much not quite justifying his title.