Prismari, the Inspiration | Expansion // Explosion

Cards

You have another instant or sorcery card in hand with the mana to cast it and applicable target(s) if needed.

Cast any other instant or sorcery by paying its mana cost.
Holding priority, cast
Expansion by paying its mana cost, targeting the instant or sorcery cast in step 1.
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.

This combo has been estimated to be Exhibition (Bracket 1+).