Increase the min deck count to like 45 or 50 cards to lower combo consistency and to free up some space to make decks more unique.

Also some kind of once per duel negate (probably any of the negates that ghost belle, ash blossom, or effect veiler can do) where they can pay a price (maybe life points or banish a card from ur hand or something) to help make breaking through unbreakable boards easier and to stop u from being screwed over if u don't draw a hand trap (it would also be able to affect monsters that are unaffected by card effects since this rule wouldn't technically be a card).

Myb some of these r dumb or are overpowered in a weird way or something, idk, I haven't thought about these ideas to hard.