Hearthpwn

 What is the interaction of this card with Commander Ulthok in warlock, is the player forced to take damage if they can't spend any mana. Also is the damage avoidable with on turn immunity effects such as Mal'Ganis, Void Virtuoso or Felstring Harp?

I'm so distracted by your grammatical choices. You ended three sentences using a comma, a period, and a question mark when you should have used a question mark all three times. I almost feel like that was intentional to screw with people, lol. 

Or more?  How much more.

And it goes on forever, or stops after the first person takes damage?

Absolutely nuts win condition, while also making both players play a whole new game on top of their match. If you pair it up with some disruption tools like Speaker Stomper, Cold Feet, or Magatha, Bane of Music, you could stall your opponent turn after turn and make them take 8 damage each time