Cheapest priced copy (Adventures in the Forgotten Realms): $0.35 at Card Kingdom, near mint, their price list as of .
White Dragon 
Creature — Dragon · 4/4 · Uncommon · Adventures in the Forgotten Realms · #288
Flying
Cold Breath — When this creature enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Adventures in the Forgotten Realms | 41 | Uncommon | $0.35 | $0.49 |
| Adventures in the Forgotten Realms | 288 | Uncommon | $0.49 | $1.49 |
One ruling from Wizards of the Coast
- 23 July 2021White Dragon's Cold Breath ability can target a tapped creature. That creature won't untap during its controller's next untap step.