El Fisto is back! He wants revenge, but he is injured. If you defeat him, you can win an algebraic rare gold card (Banshe Princess, Banshe Queen, and Unicylops) or 3 gems. Each reward card is obtained only once. There are a total of eight of these "Grudge Matches" randomly available to players during the course of the normal Fionna and Cake quests after reaching page #2. El Fisto will alert you when there is an algebraic card chance!
El Fisto Grudge Match Rewards: