Boin Islands

{t}: Gain two mana of any color.
At the beginning of your upkeep, put a +1/+1 counter on target creature.
Every three turns, destroy target creature with a +1/+1 counter on it. You gain life equal to it's toughness.
"These islands are not islands! They are in fact island-sized carnivorous plants! Every so often they'll close themselves and feed on anything on it!"