Cheapest priced copy (Zendikar Rising Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Dimir Keyrune 
Artifact · Uncommon · Zendikar Rising Commander · #110
{T}: Add {U} or {B}.
{U}{B}: This artifact becomes a 2/2 blue and black Horror artifact creature until end of turn and can't be blocked this turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.35 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends: Battle for Baldur's Gate | 856 | Uncommon | $0.39 | — |
| Gatecrash | 228 | Uncommon | $0.39 | $1.49 |
| Zendikar Rising Commander | 110 | Uncommon | $0.35 | — |
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.