Arcane Bombardment is a mythic Enchantment card from Streets of New Capenna Promos (PSNC), collector number 101s. Current market price: — (foil $32.07), TCGplayer market prices via Scryfall.
Whenever you cast your first instant or sorcery spell each turn, exile an instant or sorcery card at random from your graveyard. Then copy each card exiled with this enchantment. You may cast any number of the copies without paying their mana costs.