Cheapest priced copy (Strixhaven: School of Mages): $0.49 at Card Kingdom, near mint, their price list as of .
Efreet Flamepainter 
Creature — Efreet Shaman · 1/4 · Rare · Strixhaven: School of Mages Promos · #98p
Double strike
Whenever this creature deals combat damage to a player, you may cast target instant or sorcery card from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Strixhaven: School of Mages Promos | 98p | Rare | $0.59 | $1.49 |
| Strixhaven: School of Mages Promos | 98s | Rare | — | $0.69 |
| Strixhaven: School of Mages | 98 | Rare | $0.49 | $0.49 |
| Strixhaven: School of Mages | 310 | Rare | $0.49 | $0.99 |
3 rulings from Wizards of the Coast
- 16 April 2021If 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 spell has any mandatory additional costs, those must be paid to cast the spell.
- 16 April 2021If the card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
- 16 April 2021Efreet Flamepainter’s triggered ability lets you cast the spell immediately, ignoring timing restrictions. It doesn’t let you choose to cast it at a later time.