Niblis of Frost
Creature — Spirit
Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.
3/3
Illustrated by
Eldritch Moon Promos#72RareEnglishLegality
Rulings
Jul 13, 2016
If multiple effects say that a creature doesn’t untap during its controller’s next untap step, those effects all apply during one untap step. For example, if you cast two instants in one turn and target the same creature twice with Niblis of Frost’s ability, that creature will only spend one untap step without untapping.