Cheapest priced copy (The Lost Caverns of Ixalan): $0.35 at Card Kingdom, near mint, their price list as of .
Ancestors' Aid 
Instant · Common · The Lost Caverns of Ixalan · #132
Target creature gets +2/+0 and gains first strike until end of turn.
Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan | 132 | Common | $0.35 | $0.49 |
| The List | LCI-132 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 10 November 2023If the target of Ancestors' Aid is illegal as the spell tries to resolve, it won't resolve and none of its effects will happen. You won't create a Treasure token.