Ringing Strike Mastery 
Enchantment — Aura
Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
Enchanted creature has "
: Untap this creature."
Legality
standardLEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL