Kai, Heart of Tide

(Kai, Heart of Tide isn't a spell, it's affected by summoning sickness, and it has "{t}: Add {u}.")
Flying
{5}{u}{u}, {t}, Sacrifice Kai, Heart of Tide: Return all nonland permanents to their owners' hands, then create a 6/6 blue Elemental legendary creature token with hexproof, flying, haste, and indestructible. It has "When this creature enters the battlefield, tap all lands you control."