By letting Sakashima the Impostor enter the battlefield as a copy of Avatar Kuruk (the back face of The Legend of Kuruk), you unlock a massive Waterbend exhaust ability that grants you an extra turn for twenty mana. Because that immense cost can be subsidized by tapping your other artifacts and creatures, you can readily pull it off while Thassa, Deep-Dwelling is around to safely blink Sakashima at the beginning of your end step. This flicker resets Sakashima's once-per-game exhaust activation by making it re-enter fresh as a brand-new copy of Avatar Kuruk, allowing you to chain infinite turns and lock down the game completely.