Aquadepth Kraken

Islandwalk
{p/u}{u}{u}{t}, Exert this creature: Tap target land. It becomes an Island.
{p/u}{p/u}{p/u}{p/u}{p/u}{t}, Sacrifice this creature: Destroy up to three lands under target player's control. Up to three other lands that player controls become Islands and deal 3 damage to that player.
"What a Kraken grasps it does not lose, be it a longship or leviathan."