Stoneshock Giant (CM2) from Commander Anthology Volume II, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Lars Grant-West
• Card Text:
  6RR: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
  When Stoneshock Giant becomes monstrous, creatures without flying your opponents control can't block this turn.