Gunther's forced retirement and replacement

[Takanomiya Hijiri]

If you really wanted to do a Gambler Mage then another possible way to go about it might be instead of (or as well as) having a move for each individual card you could have his moves based on hands in Poker (or some other card game), e.g. Royal Straight Flush, Full House.
Then you could actually draw a hand of cards from a deck to see what you get to use.

https://www.cardplayer.com/rules-of-poker/hand-rankings