Simic Keyrune
Gatecrash — uncommon
Artifact
Simic Keyrune rulings:
2013-04-15: Until the ability that turns the Keyrune into a creature resolves, the Keyrune is colorless.
2013-04-15: Activating 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.