Do you "cast" copies of spells? If so, this one may belong on the Synergy couch.
{Blistercoil Weird} enchanted by {Dual Casting} to make red mana, or just cast infinitely making a huge Weird. Guttersnipe on the field means a lot of direct damage. Could it work with {Isochron Scepter}?
Effects like that only work with the initial card cast, not the copies. Notice how it says when you cast a spell? It means from the hand
Sorry to burst the bubble but copied spells arent cast.
A casted spell is a when you pay the cost for a card and put it on the stack. From anywhere. Hand (Your ordinary kind of spell, i.e. {Goblin piker}), graveyard ({Skaab Ruinator}), library ({Jace, Architect of thought}'s Ultimate) or exile ({Misthollow griffin}).
Or circumventing cost by, for example, having {Omniscience} in play.
The scepter Copies the card and lets you cast the copied card.
Dual casting just copies the spell.
{Isochron Scepter} does explicitly state "you may cast" the copy. When something copies a spell (via {Twincast} for example) it puts the copy directly on the stack rather than casting the copy.
Alright, well, it still would be a neat way to deal a lot of burn in one turn.
Play {Searing Spear}, copy it, {brimstone volley} to untap and burn them, copy it.
I might make that the one-drop in an Izard deck or something.