Turn against froze the game

Barrelrolla

I using Naheeli against Koth
I had a Tyrant on the field and it was his turn. He used his first ability which created a nice cascade for him (obviously) and he filled his hand. He played Avaricious Dragon, Devil's Playground and Turn Against, which he used to take my dragon. Then he used a spell which dealt 6? damage to my dragon and attacked. When the dragon came back to me it dealt 6 damage to him and all his creatures which caused the devils to die. Since the dragon had 2 HP left from the spell, when the devils died and dealt 4 damage, my dragon also died.
And the game froze at that point.