Narset's Reversal + Fork

Prerequisites

You have an additional instant or sorcery card in hand with valid targets as applicable.

Steps

1. Cast any instant or sorcery by paying its mana cost.
2. Holding priority, cast Fork by paying its mana cost, targeting the instant or sorcery cast in step 1.
3. Cast Narset's Reversal by paying {U}{U}, copying Fork targeting the spell cast in step 1 and returning the original Fork to your hand.
4. Cast Fork by paying its mana cost, copying the copy of Fork, targeting the copy of Fork.
5. Resolve the copy of Fork, creating a copy of Fork targeting the copy of Fork.
6. Repeat step 5.