Narset's Reversal + Storm-Kiln Artist + Bonus Round

Prerequisites

You have another instant or sorcery in hand that can be cast using at most four colored mana, with valid targets (as applicable). You have enough mana to cast the additional instant or sorcery minus one colored mana.

Steps

1. Cast Bonus Round by paying {1}{R}{R}.
2. Storm-Kiln Artist triggers, creating a Treasure token.
3. Resolve Bonus Round.
4. Cast the additional instant or sorcery by paying its mana cost.
5. Bonus Round and Storm-Kiln Artist trigger.
6. Resolve the Bonus Round trigger, copying the instant or sorcery.
7. Storm-Kiln Artist triggers. Resolve both triggers from this step and step 5, creating two Treasure tokens.
8. Activate two Treasures by tapping and sacrificing them, adding {U}{U}.
9. Cast Narset's Reversal by paying {U}{U}, targeting the spell from step 4.
10. Bonus Round and Storm-Kiln Artist trigger.
11. Resolve the Storm-Kiln Artist trigger, creating a Treasure token.
12. Resolve the Bonus Round trigger, copying Narset's Reversal targeting the original Narset's Reversal.
13. Storm-Kiln Artist triggers, creating a Treasure token.
14. Resolve the copy of Narset's Reversal, causing you to copy Narset's Reversal targeting the original spell from step 4, and then return the original Narset's Reversal to your hand.
15. Storm-Kiln Artist triggers, creating a Treasure token.
16. Resolve the copy of Narset's Reversal, copying the spell from step 4 and returning the original spell from step 4 to your hand.
17. Storm-Kiln Artist triggers, creating a Treasure token.
18. Resolve the copy of the spell from step 16.
19. Holding priority, repeat from step 4.