same strategy as in Advanced Solo version, but it seems to be harder to spot his AOE, he doesn't always say "Claws! Slash!" but will announce it in "blue text" in the chatwindow. I don't know the exact line. If you do please fill in. Might be good to have an ACT trigger set up with this line.
or tank him on the bridge and the rest of the group max range for dps heal... tank get the aoe but nothing really hurting with good healer
He can be turned into Krelgrek the Mortified. At about 80% you have a chance to click him with the cursor (turns into hand). If you don't, he will get a different name (xxx) and become the Hardmode boss.
Periodically big add-waves will join the fight. We killed the adds, though it might be possible to focus dps on the boss and ignore them if you can kill him fast and the tank can hold all the adds (who will accumulate).
Cures are the most important factor. Need a good healer, or two. If you don't cure the curse: _please insert name here_ it will one-shoot the afflicted person.