Crucible - unkillable iron maiden?

Grim Dawn Gameplay Discussion
1

So, on wave 120 of crucible I had to fight Fabius and Iron Maiden. Fabius went down easy, but I had to fight the Iron Maiden for 5+ mins and she was still 100%. Because every time I dropped her to about 70% she would heal to full. Every Time. I’ve killed Iron Maiden before without issues in the same run. It was with a level 85 character on the second tier difficulty. Is this normal behavior? If yes, how do I deal with this? I will have to let her kill me…
EDIT: After more testing, it seems she just automatically heals to full every x seconds. It has the same effect icon as Rifthound Alpha howl.

Attachment: 20161001192148_1.jpg

2

What mutators were active when this happened? She does have a menhir’s will ability, but that activates when she is on 30% health and it has a 45 second cooldown.

3

It was definetely more frequent than that. As for mutators, I’ve attached a screenshot that I took before giving up.