Yonavod, Slaver of the Void

As long as you control four or more islands, Yonavod, Slaver of the Void has hexproof.
As long as you control four or more swamps, Yonavod has indestructible.
{t}, Sacrifice an island and a swamp: Gain control of target creature an opponent controls for as long as you control Yonavod.