Twinning Staff + Narset's Reversal

Prerequisites

an instant or sorcery spell in hand. Mana available to cast the instant or sorcery spell.

Steps

1. Cast the instant or sorcery spell.
2. Holding priority, cast Narset's Reversal by paying {U}{U}, targeting the instant or sorcery spell.
3. Holding priority, activate twinning staff by paying {7} targeting Narset's Reversal, copying Narset's Reversal twice.
4. Resolve one copy of Narset's Reversal targeting another copy of Narset's Reversal, copying it twice and returning the targeted copy to your hand.
5. Repeat step 4.