Oneshot to 'The Undead Brutes'

As you can read in the title, I got oneshot by the a mob from the prophecy 'The Undead Brutes'.
Obviously, as one should, I analyze deaths to prevent them in the future.

But holy cow, there is litereally zero information about that one.
The death occured upon death of the pack as I ripped through them with my minions.
It felt like a corpse explosion though it had not the typical effect and sound of those.
The sound was more like an abyssal cry explosion. Chaos corpse explosion maybe?

Help please. First time I play non-melee characters. Ironically I keep dying :D Not being tanking is stressfull...

They don't do anything regular rare monsters cannot do. Maybe some of them had Volatile Blood. Not sure if they can spawn the zombie subtype with the chaos degen cloud on death, but if so, that is another possibility.

Ah. Okay. I'assume it was not chaos degen of any sort. I closly watched my HP. It was an instant explosion death.

It would have been avoidable if I stayed back and let my minion do their stuff.
I guess I still play to offensively ;)

Anyway, if they CAN roll normal rare mod (which I was unaware of) then it was probably corpse explosion.
I thought those prophecy mobs had a set mod on them all the time.