Phage the Untouchable + Endless Whispers

Prerequisites

You have a way to kill Phage.

Steps

1. Kill Phage, triggering its ability, causing target opponent to return Phage to the battlefield under their control from your graveyard at the beginning of the next end step.
2. At the beginning of your end step, Phage triggers, returning itself from your graveyard to the battlefield under the opponent's control.
3. When Phage enters the battlefield, its first ability triggers, causing its controller to lose the game.