Marinos, Tidebender

+1: Tap target creature. It doesn't untap during its controller's next untap step if that player controls an Island.
-2: Flood target land. Scry X, where X is the number of Islands your opponents control.
-7: Gain control of all Islands. Islands become 2/2 blue Merfolk creature tokens with "This creature can't be blocked." They are still lands.