Cheapest priced copy (Oath of the Gatewatch): $0.35 at Card Kingdom, near mint, their price list as of .
Pyromancer's Assault 
Enchantment · Uncommon · Oath of the Gatewatch · #115
Whenever you cast your second spell each turn, this enchantment deals 2 damage to any target.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Oath of the Gatewatch | 115 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 22 January 2016The ability can trigger only once each turn. The ability will resolve before the second spell resolves. It doesn’t matter if the first spell you cast that turn has resolved, was countered, or is still on the stack.