Narset's Reversal | Expansion // Explosion

Cards

You have an additional instant or sorcery card in hand with mana value 4 or less and valid targets as applicable.

({U} magic symbol) ({U} magic symbol) ({UR} magic symbol) ({UR} magic symbol) plus enough mana to cast the additional instant or sorcery available.

Cast any 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.
Cast
Narset's Reversal by paying ({U} magic symbol) ({U} magic symbol) , copying
Expansion targeting the spell cast in step 1 and returning the original
Expansion to your hand.
Cast
Expansion by paying its mana cost, copying the copy of
Expansion, targeting the copy of
Expansion.
Resolve the copy of
Expansion, creating a copy of
Expansion targeting the copy of
Expansion.
Repeat step 5.

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