Cheapest priced copy (Avatar: The Last Airbender Eternal): $0.99 at Card Kingdom, near mint, their price list as of .
Lost in Memories 
Enchantment — Aura · Rare · Avatar: The Last Airbender Eternal · #121
Flash
Enchant creature you control
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost." (You may cast that card from your graveyard for its flashback cost. Then exile it.)
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 to $1.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Avatar: The Last Airbender Eternal | 121 | Rare | $0.99 | $0.49 |
| Avatar: The Last Airbender Eternal | 195 | Rare | $1.29 | $0.79 |
6 rulings from Wizards of the Coast
- 2 October 2025You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.
- 2 October 2025You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.
- 2 October 2025To determine the total cost of a spell, start with the mana cost or alternative cost (such as a flashback cost) you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
- 2 October 2025"Flashback [cost]" means "You may cast this card from your graveyard by paying [cost] rather than paying its mana cost" and "If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack."
- 2 October 2025If a card with flashback is put into your graveyard during your turn, you can cast it if it's legal to do so before any other player can take any actions.
- 2 October 2025A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way.