Necro-Impotence 
Enchantment
Skip your untap step. At the beginning of your upkeep, you may pay X life. If you do, untap X permanents. Pay ½ life: Exile the top card of your library face down. Put that card into your hand at the beginning of the next end step.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL