* New Card Mastery System:

Once a card reaches level 6, you can unlock its mastery to further upgrade that cards power.

Upon purchasing the first mastery for a card, the max level of that card rises to level 12, and that card is available to pull in the pool of available cards again. The number of cards required to upgrade each level remains fixed at 20 cards.

Unlocking mastery levels also adds a secondary set of bonuses that improve each mastery level.