Hythonia the Cruel (THS) from Theros, available at 401 Games Canada.

• Rarity: Mythic Rare
• Finish: Normal
• Artist: Chris Rahn
• Card Text:
  Deathtouch
  6BB: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
  When Hythonia the Cruel becomes monstrous, destroy all non-Gorgon creatures.