See above. Enemies death AoE triggers after Calibretto’s perk that should happen at the very end of combat. Losing some HP generation this way.
Did the werewolf have any damage over time debuff when this happened? I’ve noticed that during certain circumstances when there is a heal that’s supposed to go off before the enemy’s turn, the order would go backwards. Before end of combat the enemy’s debuff (burning/bleeding) would trigger first then die (exploding) followed by Bretto healing. I’m wondering in your case the roll was flipped?