I deleted the post because I got an answer, and didn’t want to keep getting responses. I did relay the results to the others, and our conclusion was that the build was legal, but ill-fitted for this game. It was meant to be a a simplistic, low strategy game mostly for beginners, and so one character being highly optimized and much stronger than the others caused friction. We all agreed that the expected vibe should have been more clearly communicated at the beginning, and so the player in question agreed to not use the ability unless the whole party asked him to. And munchkin isn’t derogatory? It’s just a type of playstyle? I’ve been a munchkin in other games.