Cheapest priced copy (Return to Ravnica): $0.35 at Card Kingdom, near mint, their price list as of .
Golgari Keyrune 
Artifact · Uncommon · Return to Ravnica · #229
{T}: Add {B} or {G}.
{B}{G}: This artifact becomes a 2/2 black and green Insect artifact creature with deathtouch until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Return to Ravnica | 229 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 15 April 2013Until the ability that turns the Keyrune into a creature resolves, the Keyrune is colorless.
- 15 April 2013Activating the ability that turns the Keyrune into a creature while it's already a creature will override any effects that set its power and/or toughness to another number, but effects that modify power and/or toughness without directly setting them will still apply.