Cheapest priced copy (Tarkir: Dragonstorm Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Hammerhead Tyrant 
Creature — Dragon · 6/6 · Rare · Tarkir: Dragonstorm Commander · #21
Flying
Whenever you cast a spell, return up to one target nonland permanent an opponent controls with mana value less than or equal to that spell's mana value to its owner's hand.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tarkir: Dragonstorm Commander | 21 | Rare | $0.49 | — |
| Tarkir: Dragonstorm Commander | 61 | Rare | $1.49 | — |
2 rulings from Wizards of the Coast
- 4 April 2025If a spell has {X} in its mana cost, use the value of X chosen as it was cast to determine that spell’s mana value.
- 4 April 2025If a permanent has {X} in its mana cost, X is 0 for the purpose of determining its mana value.