Cheapest priced copy (Ixalan): $0.35 at Card Kingdom, near mint, their price list as of .
River Heralds' Boon 
Instant · Common · Ixalan · #204
Put a +1/+1 counter on target creature and a +1/+1 counter on up to one target Merfolk.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ixalan | 204 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 29 September 2017You can choose one Merfolk creature as both targets for River Heralds’ Boon. You can also choose two different Merfolk creatures.