Arbor Colossus (C15 174)

Creature — Giant • Mana cost: {2}{G}{G}{G} • Commander 2015 • Rare

Reach
{3}{G}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
When this creature becomes monstrous, destroy target creature with flying an opponent controls.

Illustrated by Jaime Jones.