Flip monsters (Japanese: リバースモンスター Ribāsumonsutā "Reverse Monster"), formerly Flip Effect Monsters (リバース
While some Flip monsters have effects other than their Flip effect, any monster with a Flip effect is a Flip monster.
A Flip effect is a type of Trigger Effect that is preceded by "FLIP:". This kind of effect is triggered when the monster on the field is fliped from face-down to a face-up, even during the Damage Step.
Some monsters have effects with the timing "when this card is flipped face-up" (unofficially called Pseudo-Flip Effects), such "Snowman Eater", which while mechanically identical are different from Flip effects.
When a face-down Flip monster is attacked, during damage calculation the monster is flipped face-up, then it is determined whether or not the monster is destroyed by battle. Near the end of the Damage Step, before being sent to the Graveyard if it was destroyed by battle, the Flip monster's Flip effect activates and resolves on the field, if the timing is correct.
However, if a card effect destroys a face-down Flip monster, its Flip effect cannot be activated since it is not flipped face-up. If a face-down Flip monster is destroyed by a card effect before it battles (so it is never flipped face-up), such as by "Ancient Gear Beast", its Flip effect cannot be activated.
- So far, there are no Dragon, Dinosaur, Fish and Sea Serpent-Type Flip monsters.
- Only 6 Flip monsters are Level 5 or higher ("Hade-Hane", "Nobleman-Eater Bug", "Reaper of the Cards", "Shaddoll Beast", "Worm Noble" and "Worm Victory").
- Flip monsters are rarely used in the anime, in which prior to Yu-Gi-Oh! ZEXAL it was legal to Normal Summon a monster in Defense Position, and Set monsters were rarely seen.
- "Cyber Jar", "Fiber Jar", "Magician of Faith", "Morphing Jar" and "Morphing Jar #2" are the only Flip monsters to ever be Forbidden (the last two only on the TCG).
- "Worm Victory" has the highest Level and DEF of all Flip monsters. "Slate Warrior" has the highest ATK of all Flip monsters.