Level 40 Warlock Lost

Hello everyone. I was just wondering if someone else has experienced this. I lost my level 40 warlock to a story quest. It was the one where you light the pyre to signal the amazons to come, and you go through a gauntlet of hellgates. I was experimenting with a new build because I was bored with my previous one, and this one was also working quite well. I’d just basically cleared the entire screen in a few button presses when I was struck by an attack. I don’t know what the attack was, but it poisoned my entire health bar instantly. I used 4 potions spread apart and my defensive abilities, but I still died from it. It effectively did 400% of my HP from a single instance of poison. My official death reads, “Ashen Clawer.” Does anyone know if there is an affix that enemies can get that does that? I was on Penintent difficulty at the time.