Cheapest priced copy (Outlaws of Thunder Junction Commander): $7.99 at Card Kingdom, near mint, their price list as of .
Arcane Bombardment 
Enchantment · Mythic · Streets of New Capenna · #422
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.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $7.99 to $27.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Outlaws of Thunder Junction Commander | 154 | Mythic | $7.99 | — |
| Streets of New Capenna Promos | 101p | Mythic | $14.99 | $27.99Out of stock |
| Streets of New Capenna Promos | 101s | Mythic | — | $14.99 |
| Streets of New Capenna | 101 | Mythic | $7.99 | $7.99 |
| Streets of New Capenna | 422 | Mythic | $7.99 | $13.99 |
5 rulings from Wizards of the Coast
- 29 April 2022If you cast a spell with {X} in its cost without paying its mana cost, you must choose 0 for X.
- 29 April 2022The spell that caused Arcane Bombardment's ability to trigger is normally still on the stack while that ability resolves. That spell won't be among the cards in your graveyard when you exile an instant or sorcery from it at random.
- 29 April 2022If you've already cast an instant or sorcery spell the turn that Arcane Bombardment enters the battlefield, it won't trigger until you cast an instant or sorcery spell on a later turn.
- 29 April 2022If Arcane Bombardment leaves the battlefield, the exiled cards remain in exile. If it returns to the battlefield or you play another copy of it, you won't get to cast copies of the cards previously exiled.
- 29 April 2022You cast the desired copies as the triggered ability resolves. You don't get to cast them later in the turn. You choose the order of copies as you cast them.