Boulder Salvo
Sorcery
Surge 
(You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Boulder Salvo deals 4 damage to target creature.
"If someone claims the sky is falling, I listen." —Yon Basrel, Oran-Rief survivalist
Illustrated by
The List#OGW-102CommonEnglishLegality
Rulings
For some cards, surge represents only an alternative cost, a discount that applies if you or a teammate has cast another spell this turn. Other cards, like Reckless Bushwhacker, have additional abilities or effects if you paid the surge cost to cast the spell.
The other spell that you or a teammate cast can be one that’s resolved, one that was countered, or (for instants with surge) one that’s still on the stack.
If an instant or sorcery spell cast for its surge cost is copied, the copy is also considered to have had its surge cost paid.
Casting a spell for its surge cost doesn’t change its mana cost or its converted mana cost.