You can upgrade cards in one of two ways: earning Boosters and Fast Upgrades.

Earning Boosters:

At the end of a match, you will earn Boosters for a card that was in your deck.

You earn 1 Booster for each turn played.

When you have enough Boosters, you will see the card is able to be upgraded via notification pips and upgrade arrows in the collection.

Fast upgrades:

In the shop, you will see 3 cards you can instantly upgrade by paying credits.

The price of the upgrade is reduced for every booster you already have for the card.

Every 8 hours, 3 different cards will be randomly selected from your collection