Sub-Zero Atmospher interupting attacks?

This scenario came up with Absolute Zero (Elemental Wraith) against Iron Legacy. Sub-Zero Atmosphere was in play, meaning Iron Legacy deals each hero target 3 melee damage at the START of the turn instead. Once, it was enough damage (due to modifiers) to Incapacitate Absolute Zero. We chose to have him take the damage first. We assumed this meant that, now that Sub-Zero Atmosphere was gone and Iron Legacy's attack returned to being at the end of a turn, his attack would stop. Was the the correct assumption, or would he still have attached the other hero targets?

My opinion: damage would stop, but he would then do that damage to all remaining heros at the end of his turn. 

Agree with Foote and you.

Damage would stop, his start of turn effect reverts to an end of turn effect.

This card and Twist the Ether are so far the most "fun" cards to deal with in the game rules engine =). I took a note when this happened in our game, and indeed it's not being handled correctly. We'll get it fixed!

I would probably have played it as the effect has started so carries on as there’s nothing specifically interrupting it as such, sub zero atmosphere has had its effect when the attack started, and then the attack goes off at the end of turn again.
Any further cards waiting to go off wouldn’t and would revert to just end of turn. They’ve been interrupted before they started by the removal of Absolute Zero’s cards.

But I may be a little vicious.

Foote and Matchstickman are correct!

The newly considered "start of turn" effect damage would interupt as soon as the effect stops being "start of turn", hence damage interupts when AbZero leaves play.

Ah, nice to know, as he can be a rough enough fight anyway.