Cheapest priced copy (Dominaria Remastered): $3.49 at Card Kingdom, near mint, their price list as of .
Gauntlet of Power 
Artifact · Rare · Time Spiral · #255
As this artifact enters, choose a color.
Creatures of the chosen color get +1/+1.
Whenever a basic land is tapped for mana of the chosen color, its controller adds an additional one mana of that color.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
7 printings · $3.49 to $59.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria Remastered | 223 | Mythic | $4.49 | $4.99 |
| Dominaria Remastered | 378 | Mythic | $3.49 | $6.99 |
| Dominaria Remastered | 447 | Mythic | $3.99 | $6.99 |
| Kaladesh Inventions | 12 | Special | — | $59.99 |
| The List | TSP-255 | Rare | $4.99 | — |
| Time Spiral | 255 | Rare | $4.49 | $6.99 |
| Time Spiral Remastered | 267 | Mythic | $4.99 | $5.99 |
2 rulings from Wizards of the Coast
- 8 December 2022Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a creature of the chosen color may become lethal if Gauntlet of Power leaves the battlefield during that turn.
- 8 December 2022If Gauntlet of Power is somehow on the battlefield with no color chosen for its first ability, no creatures get +1/+1 and its last ability never triggers. It still won't affect colorless creatures or basic lands tapped for colorless mana.