Cheapest priced copy (Teenage Mutant Ninja Turtles): $0.35 at Card Kingdom, near mint, their price list as of .
Retro-Mutation 
Enchantment — Aura · Common · Teenage Mutant Ninja Turtles · #51
Flash
Enchant creature
Enchanted creature is a Turtle with base power and toughness 0/1. It can't attack and loses all abilities. (It also loses all other creature types.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Teenage Mutant Ninja Turtles | 51 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 27 January 2026Retro-Mutation overwrites all previous effects that set the creature's base power and toughness to specific values. Any power- or toughness-setting effects that start to apply afterward will overwrite this effect.
- 27 January 2026Effects that modify the creature's power and/or toughness, such as the effect of Karai's Technique, will apply to the creature no matter when they started to take effect. The same is true for counters that change its power and/or toughness and effects that switch its power and toughness.