These card ideas were based off the new Commander 2013 commanders (see Jeleva, Nephalia's Scourge).
Either:
Shattering Storm

Sorcery
Destroy X target artifacts, where X is the amount of mana spent to cast Shattering Storm.
Or:
Shattering Storm

Sorcery
Shattering Storm is Red.
If

was spent to cast Shattering Storm, destroy X target artifacts, where X is the amount of mana spent to cast Shattering Storm.
I think I like the second one more, as it is more situationally useful, but the wording is more complicated. It is also less helpful against T1 Lodestone/Chalice at 0.
Neither is strictly superior to Shattering Spree despite the easier mana requirements; whether one would prefer these to that would depend on the number of sphere effects they have in play. They both do well against openers like T1 Trinisphere, T2 Golem, T3 Golem/Sphere.
Tell me what you think.