Cheapest priced copy (Theros): $0.35 at Card Kingdom, near mint, their price list as of .
Wavecrash Triton 
Creature — Merfolk Wizard · 1/4 · Common · Theros · #74
Heroic — Whenever you cast a spell that targets this creature, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Theros | 74 | Common | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 15 September 2013Heroic abilities won't trigger when a copy of a spell is created on the stack or when a spell's targets are changed to include a creature with a heroic ability.
- 15 September 2013Wavecrash Triton's 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.
- 15 September 2013Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.
- 15 September 2013Heroic abilities will resolve before the spell that caused them to trigger.
- 15 September 2013Wavecrash Triton's ability can target a creature that's already tapped. That creature still won't untap during its controller's next untap step.