I was fighting tekahn heroic mode. It was my turn almost had him down to 200hp I played the summon 7 murloc treasure then both hero plates exploded and it said I lost? I feel like it did this to me in non heroic as well once and I reported it but never got an answer. Reallllly irritating when you are on track to win and you get destroyed by some bug…
Known issue with Murky’s Battle Horn:
When both heroes die at the same time, you see a “Lost” screen, but it is recorded as a Draw, and in an Adventure, a Draw means you do not progress to the next boss level, you instead get to fight a boss of the same level again. In the case of Tekahn, that would mean restarting the fight with him. If your run ended, that that is another bug to add to the already acknowledged one.