Cheapest priced copy (Commander 2020): $0.49 at Card Kingdom, near mint, their price list as of .
Niblis of Frost 
Creature — Spirit · 3/3 · Rare · Eldritch Moon · #72
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.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2020 | 120 | Rare | $0.49 | — |
| Eldritch Moon | 72 | Rare | $0.69 | $2.49 |
| Eldritch Moon Promos | 72 | Rare | — | $1.49 |
| Eldritch Moon Promos | 72s | Rare | — | $3.49 |
One ruling from Wizards of the Coast
- 13 July 2016If 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.