Is this really active skill? I suppose this is a passive skill.
Yes this is active but the description is very vague. I think it's supposed to be more along the lines of: "Breaths fire on his axe to increase damage". We'll look at getting this changed.
I edited the tooltip to:
Breath fire on your axe to increase its damage dealing.
It will be included in a future release. Thanks for reporting the issue
Customer support service by UserEcho