While exploring and making your way through Griftlands, you have a variety of unique cards you use during different situations from two decks, your negotiation deck, and your battle deck. You can level up these cards in each deck, and eventually have them upgrade into a better version of the regular card. The traditional way is to use them enough times during encounters, but you may find random events in the game where you can choose to upgrade a card from one of these decks.
Most of your cards from your negotiation and battle decks should have a small bar at the top of them, showing how much experience points they need before leveling up. You gain experience points with these cards by using them in encounters. The experience points you earn following each use of the card carry over into other battles until you use them enough times to have the option to upgrade them.
The experience point requirements vary for your cards. Some may require only three uses, whereas others require seven. You can inspect a card by viewing your decks at the top right of your screen and investigate the various upgrade options, or you can do it during an encounter.
An alternative method for upgrading a card comes from a random event. The type of events vary, and they happen while you are heading to a location on the map. During the event, you will have a list of options to choose from on your screen. Before selecting a choice for how to react, you can see the outcome and the results before accepting it. If you see an option to upgrade a card from your negotiation or battle deck, choose it to improve any of the cards held in your deck automatically.
The upgraded card will remain on your character for the remainder of your run. However, if your character dies, you will lose all of a card’s experience points and start over.