Mechanics refer to additional game mechanics that were added to the normal rules, usually only featured in one set, and that add complexity and new rules to the game.
- Madness cards (The Obligatory Cthulhu Set), which give VP penalty at the end of the game to players who didn't manage to get rid of them.
- +1 Power Counters (Monster Smash), mainly an alternate way to boost a minion's power.
- Monsters (Smash Up: Munchkin), minions that add their power to the bases' breakpoints and make them harder to break.
- Treasures (Smash Up: Munchkin), minion and action cards that are given as rewards for players who defeat the monsters.
- Titans (Big in Japan), gigantic creatures that act as the twenty-first card of their faction.
- Burying (Oops, You Did It Again), the ability to play cards face-down on a base.
- Duels (Oops, You Did It Again), during which two players face off to get a reward, or avoid a punishment.