FOILCheapest priced copy (Shadows over Innistrad): $0.49 at Card Kingdom, near mint, their price list as of .
Corrupted Grafstone 
Artifact · Rare · Shadows over Innistrad Promos · #253s
This artifact enters tapped.
{T}: Choose a color of a card in your graveyard. Add one mana of that color.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shadows over Innistrad Promos | 253s | Rare | — | $1.99 |
| Shadows over Innistrad | 253 | Rare | $0.49 | $0.49 |
2 rulings from Wizards of the Coast
- 8 April 2016Players can't respond to mana abilities, so no player can take any action to stop you from getting the color of mana you expect to produce once you announce the ability.
- 8 April 2016Colorless cards have no color, so you can't add {C} this way.