Unstable Mutation

Enchantment - Aura, U (1)
Enchant creature

Enchanted creature gets +3/+3.

At the beginning of the upkeep of enchanted creature's controller, put a -1/-1 counter on that creature.¹
Illus. Douglas Shuler

Gatherer Card Rulings [Nov 2009]

• 8/1/2005: The -1/-1 counters stay even if the Aura is removed, and the +3/+3 goes away when the Aura does.

Format Legality	Legal in Vintage, Legacy, Extended, MTGO Classic Banned in Standard
Printings (5/31)	Time Spiral "Timeshifted" (Special) Fifth Edition (Common) Fourth Edition (Common) Revised Edition (Common) Arabian Nights (Common (C5))