Singing Bell Strike

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
Enchanted creature has "{6}: Untap this creature."

The List

Khans of Tarkir

Enchant creature
When Singing Bell Strike enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
Enchanted creature has "{6}: Untap this creature."

Singing Bell Strike can be cast targeting any creature, including one that's already tapped.

The activated ability that untaps the creature is granted to the enchanted creature. Only the creature's controller can activate this ability.