Gilled Hydra

As long as you control at least 3 Islands, Gilled Hydra has Trample.
If you control at least 5 Islands, you may exile Gilled Hydra from the battlefield at any time, keeping all +1/+1 counters with it. If Gilled Hydra is exiled this way, return it to the battlefield at the beginning of your next upkeep with 2 additional +1/+1 counters on it.