Ooze Flux (GTC) from Gatecrash, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Zoltan Boros
• Card Text:
  1G, Remove one or more +1/+1 counters from among creatures you control: Put an X/X green Ooze creature token onto the battlefield, where X is the number of +1/+1 counters removed this way.