First, its "Mak'gora", and no, that rule does NOT exist.
Its Might vs Might. Straight up. Always has been. I have no idea where this insane-ass idea that you cant use magic or magic weapons (what, Grom wouldn't have been allowed to use his personal weapon, Gorehowl, in a Mak'gora? Give me a break) came from, but it has never been true.