Phage spell and causing an opponent to also copy the
Phage spell.
Resolve the opponent's copy of
Phage, causing the opponent to create a token copy of it. When the
Phage token enters, its first ability triggers, causing its controller to lose the game.
Notes
If for some reason the
Phage copy created by the opponent doesn't cause them to lose the game (either via an effect prohibiting them from losing, the spell being countered, etc.), you will then lose the game when your copy of the