Cheapest priced copy (Shadowmoor): $0.35 at Card Kingdom, near mint, their price list as of .
Prismwake Merrow 
Creature — Merfolk Wizard · 2/1 · Common · Shadowmoor · #46
Flash
When this creature enters, target permanent becomes the color or colors of your choice until end of turn.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shadowmoor | 46 | Common | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 1 May 2008You can choose any single color or any combination of more than one color. You can’t choose colorless.
- 1 May 2008An effect that changes a permanent’s colors overwrites all its old colors unless it specifically says “in addition to its other colors.” For example, after Cerulean Wisps resolves, the affected creature will just be blue. It doesn’t matter what colors it used to be (even if, for example, it used to be blue and black).
- 1 May 2008Changing a permanent’s color won’t change its text. If you turn Wilt-Leaf Liege blue, it will still affect green creatures and white creatures.
- 1 May 2008Colorless is not a color.
- 1 May 2008This ability won’t make an artifact stop being an artifact. It’ll just be a colorful artifact.