Erratic Mutation
Instant
Choose target creature. Reveal cards from the top of your library until you reveal a nonland card. That creature gets +X/-X until end of turn, where X is that card's mana value. Put all cards revealed this way on the bottom of your library in any order.
Legalities
- brawl: banned
- commander: legal
- legacy: legal
- modern: legal
- pauper: legal
- pioneer: banned
- standard: banned
- vintage: legal
Rulings
- 2021-03-19:
If a card in a player’s library has {X} in its mana cost, X is considered to be 0.
- 2021-03-19:
You reveal cards and the creature gets +X/-X all while Erratic Mutation is resolving. Nothing can happen in between, and no player can take actions.