Low one active zerk instant death cause found

Description of the bug:
if any skill that takes away hp (slash blast, booster, roar, sacrifice, fury, and etc) does not take hp and you cast active zerk the next hit, no matter what it is, will instantly kill you.

What is supposed to happen?:
hp is supposed to be taken and you should survive any hit you take after casting active zerk

Where did you find and/or notice this bug?:
horntail

A step-by-step guide to re-producing this bug (optional):
No idea how to get hp taking skills not to take hp, but once you perform a skill that takes hp and it does not take any, start active zerk and run into anything that does damage.