Arcane Bombardment, Prismari Command, and Return the Favor

Prerequisites

• Arcane Bombardment on the battlefield
• Prismari Command in exile
• Return the Favor in hand
• undefined plus the mana needed to cast the additional instant/sorcery available

Steps

1. Cast any other instant or sorcery by paying its mana cost, triggering Arcane Bombardment
2. Holding priority, cast Return the Favor by paying and then choosing to pay an additional to select its first mode, copying the Arcane Bombardment trigger
3. 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
4. As you cast the Return the Favor copy, choose to pay an additional to select its first mode, targeting the Arcane Bombardment trigger
5. Resolve the copy of Prismari Command, creating a Treasure token and choosing any other mode
6. Activate the Treasure by tapping and sacrificing it, adding
7. Resolve the copy of Return the Favor, copying the Arcane Bombardment trigger
8. Repeat from step 3

Results

• Infinite damage
• Infinite storm count
• Infinite magecraft triggers
• Infinite draw triggers for any number of players
• Infinite looting for any number of players
• Infinite self-discard triggers for any number of players