Approach of the Second Sun + Narset's Reversal

Steps

1. Cast Approach of the Second Sun for {6}{W}.
2. Holding priority, cast Narset's Reversal by paying {U}{U} targeting Approach of the Second Sun, copying Approach of the Second Sun and then returning Approach of the Second Sun to your hand.
3. Resolve the copied Approach of the Second Sun, gaining seven life.
4. Cast Approach of the Second Sun for {6}{W}, winning the game.