Green Mountain Dragon

{3}{g}{g}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as Green Mountain Dragon is monstrous, it has flying.
Ferocious- At the beginning of your upkeep if you control a creature with power 4 or greater, you may destroy target artifact or enchantment.