Cheapest priced copy (Return to Ravnica): $0.35 at Card Kingdom, near mint, their price list as of .
Rakdos Keyrune 
Artifact · Uncommon · Return to Ravnica · #232
{T}: Add {B} or {R}.
{B}{R}: This artifact becomes a 3/1 black and red Devil artifact creature with first strike until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| RNA Guild Kit | 75 | Uncommon | $0.69 | — |
| Return to Ravnica | 232 | Uncommon | $0.35 | $0.79 |
2 rulings from Wizards of the Coast
- 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.
- 15 April 2013Until the ability that turns the Keyrune into a creature resolves, the Keyrune is colorless.