Unstable Mutation (3ED) from Revised Edition, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Douglas Shuler
• Card Text:
  Target creature gains +3/+3. During the upkeep phase of each of its controller’s turns, put a -1/-1 counter on the creature. These counters remain even if this enchantment is removed before the creature dies.