Declare any creature as an attacker, attacking an opponent unable to block it.
When the creature is unblocked, activate Phage's ninjutsu ability by paying ({2} magic symbol) ({U} magic symbol) ({B} magic symbol) and returning the unblocked creature to your hand, putting Phage onto the battlefield tapped and attacking.
Phage enters the battlefield, triggering its ability.
Holding priority, cast Angel's Grace by paying ({W} magic symbol) , preventing you from losing the game this turn.
Resolve Phage's ability, not losing the game due to Angel's Grace.
Deal combat damage with Phage.
Phage triggers, causing the opponent to lose the game.