Your goal is to climb as high as possible in the tower. If your HP drops to 0, the game is over.
Each turn you draw 5 cards and have 3 energy. Enemies show their intentions (Attack, Block, Buff) above their heads. Use this to decide strategically whether to attack or block.
After each battle you gain gold and can choose new cards. In shops you can buy relics that grant you permanent passive bonuses.