Cheapest priced copy (Khans of Tarkir): $0.35 at Card Kingdom, near mint, their price list as of .
Quiet Contemplation 
Enchantment · Uncommon · Khans of Tarkir · #50
Whenever you cast a noncreature spell, you may pay {1}. If you do, tap target creature an opponent controls and it doesn't untap during its controller's next untap step.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Khans of Tarkir | 50 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 20 September 2014The ability tracks the creature, but not its controller. If the creature changes controllers before its first controller’s next untap step has come around, then it won’t untap during its new controller’s next untap step.
- 20 September 2014The ability can target a creature that’s already tapped. It still won’t untap during its controller’s next untap step.
- 20 September 2014You decide whether to pay {1} as the triggered ability resolves.