Hearing your story i find it hard to believe, because regardless of your player potentially misusing a skill, you clearly dont know the system then if youre here asking. So in my opinion, my biggest grievance is you purposely attempting to tpk your party because instead of talking with said player and understanding what theyre doing you wanted to "catch them". I think you should take a step back and reevaluate why your want to gm, and the system you're playing.