How about this.

We introduce a Rune system. Runes are unlocked in a battle and give powerful abilities etc. They are unlocked by playing cards and older cards give a heavy multiplier towards unlocking them. Something like what we have for the PPs on land. I could imagine playing 1 alpha or beta and unlocking runes or a single rune powerful enough to make them competitive against new cards. This could be adjusted for modern and wild.