Can anyone explain how this skill is supposed to work ? I went to try it out yesterday. I got my wear at 35/30 so it would let me use the skill, I used it and it said "Has no effect". I had like 500 GP when I used it, so I used the skill 10 times in a row thinking maybe it was an RNG proc or something and every time it said "Has no effect".

What am I doing wrong ?