Winter's Rest 
Snow Enchantment — Aura
Enchant creature When this Aura enters, tap enchanted creature. As long as you control another snow permanent, enchanted creature doesn't untap during its controller's untap step.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL