Cheapest priced copy (Final Fantasy Commander): $9.99 at Card Kingdom, near mint, their price list as of .
Duelist's Flame 
Instant · Rare · Final Fantasy Commander · #452
Until end of turn, target blocked creature you control gets +X/+0 and gains trample and "Whenever this creature deals combat damage to a player, look at that many cards from the top of your library. Exile up to one nonland card from among them and put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost."
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $5.99 to $9.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Final Fantasy Commander | 452 | Rare | $9.99 | $5.99 |
3 rulings from Wizards of the Coast
- 2 October 2025If the exiled card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
- 2 October 2025If you cast a spell "without paying its mana cost," you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, you must pay those to cast the spell.
- 2 October 2025You cast the exiled card while the triggered ability ability is resolving and still on the stack. You can't wait to cast it later in the turn. Timing restrictions based on the card's type are ignored.