Unstable Mutation 
Enchantment — Aura
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.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL
Prints
Ultimate Masters
EN · UMA · 2018-12-07
Time Spiral Timeshifted
EN · TSB · 2006-10-06
Fifth Edition
EN · 5ED · 1997-03-24
Fourth Edition
EN · 4ED · 1995-04-01
Summer Magic / Edgar
EN · SUM · 1994-06-21
Revised Edition
EN · 3ED · 1994-04-11
Arabian Nights
EN · ARN · 1993-12-17
Fourth Edition Foreign Black Border
ES · 4BB · 1995-04-01
Foreign Black Border
FR · FBB · 1994-04-11