Enchant creature with power 3 or less
When Runner's Bane enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
4/15/2013 If the enchanted creature’s power increases to 4 or greater, Runner’s Bane will be put into its owner’s graveyard as a state-based action.
4/15/2013 The enchanted creature can still be untapped in other ways, such as by Aurelia, the Warleader.