Deca Slayer brings the gameplay of the classic Decathlon into a fantasy setting, turning each match into an epic hunt against ten monsters guarding treasures and secrets. Players take on the role of adventurers, each with a deck of cards representing skills, gear, and tricks. At the start of each round, a monster appears and imposes a unique rule: it could be the highest card of a suit, the majority of cards with a specific ability, or the total sum of cards in hand. To win, players bid adventure cards, sometimes face‑up and sometimes face‑down, in a strategic duel that blends auction, hand management, and deck building. If a player fails to defeat the monster, they earn the right to receive replacement adventure cards, which can swing the game in later rounds. The game ends when the final monster, the dragon, is slain, and the winner receives bonus points. Afterward, all players tally treasure and victory points, and the one with the highest total wins. The game is quick (30 minutes), supports 3 to 6 players, and mixes auction, open drafting, and trick‑taking mechanics, providing a light yet strategic experience that appeals to both card lovers and fantasy adventurers. Deca Slayer was launched via Kickstarter, reflecting a community of players seeking an innovative and fun product.