Arcane Bombardment | Prismari Command | Return the Favor

Cards

({2} magic symbol) ({R} magic symbol) ({R} magic symbol) plus the mana needed to cast the additional instant/sorcery available.

Cast any other instant or sorcery by paying its mana cost, triggering
Arcane Bombardment.
Holding priority, cast
Return the Favor by paying ({R} magic symbol) ({R} magic symbol) and then choosing to pay an additional ({1} magic symbol) to select its first mode, copying the
Arcane Bombardment trigger.
Resolve the copy of the
Arcane Bombardment trigger, exiling
Return the Favor from your graveyard and then copying
Return the Favor,
Prismari Command and all other cards exiled by
Arcane Bombardment, and allowing you to cast those copies without paying their mana costs.
As you cast the
Return the Favor copy, choose to pay an additional ({1} magic symbol) to select its first mode, targeting the
Arcane Bombardment trigger.
Resolve the copy of
Prismari Command, creating a Treasure token and choosing any other mode.
Activate the Treasure by tapping and sacrificing it, adding ({1} magic symbol) .
Resolve the copy of
Return the Favor, copying the
Arcane Bombardment trigger.
Repeat from step 3.