April O'Neil, Human Element (TMC 107)

Legendary Creature — Human Detective • Mana cost: {3}{U} • Teenage Mutant Ninja Turtles Eternal • Rare

Whenever a player casts an artifact, instant, or sorcery spell, you create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")

"If you steal mutagen that doesn't exist from aliens that also don't exist, it's not really theft. More like creative writing!"

Illustrated by Fahmi Fauzi.