Prismari, the Inspiration, and Expansion // Explosion

Prerequisites

• Prismari, the Inspiration on the battlefield
• Expansion // Explosion in hand
• available

Steps

1. Cast any other instant or sorcery by paying its mana cost
2. Holding priority, cast Expansion by paying its mana cost, targeting the instant or sorcery cast in step 1
3. Expansion's storm ability triggers, creating at least one copy of Expansion targeting the original Expansion Resolve a copy of Expansion, copying Expansion targeting the original Expansion Repeat step 4

Results

• Infinite magecraft triggers