Zalmarath the Colossus bugged

Zalmarath dishes out damage to you and your party, but you can't damage him consistently. You start to hit him but then then nothing, just a hitless battle.

I have the same thing, I'm playing frostbolt/cold snap/comet and he's completely unhittable.

Yep he is bugged.

You have to directly exit the game, then rejoin, and wait for him to enter the next phase(when he is shooting the tiny red lazer drops and moves 90 degrees around the dial).

I had to do this three times in one fight to win it.

Great game.

Good call, reset worked.

+1

I'm also having issues with Zalmarath, on PC:

Boss becomes impervious during the fight, seemingly at random. My attacks just pass through him and he cannot be damaged at all, until I reset the fight.

I fall through the floor in the arena. Seems to happen when I roll near the edge and/or when he does his arm sweep attack.

These have all been issues since at least 0.1.

Also this is a design issue, but none of this boss's attacks can be parried. Not even the adds in the second half (the cold explosion spinning robots) can be parried. So there's no way to build up frenzy charges as huntress.