Fury Storm

Twincast with a scaling clause bolted to the front, and the scaling is what turns a generic red copy spell into something that only makes sense in one format. The base half copies a target instant or sorcery: unremarkable, the kind of effect red has printed in a dozen shells. The cast trigger is the reason it exists. It counts how many times you've cast your commander from the command zone this game (the first cast counts, tax or no tax, alongside every recast after) and banks an extra copy of itself for each, so what you are really duplicating is not just the targeted spell but your whole track record of leaning on that general. Note the wording: the trigger cares about casting, not merely leaving the zone. A commander that reaches the battlefield another way (put there by a sneak-in effect rather than cast) adds nothing to the count, no matter how many times it has cycled through the command zone. That reframes what red copy magic is for. A plain Twincast is a value trick or a combo piece cast in isolation; this pays back an investment you have to have already made. The two halves resolve independently, which cuts both ways: the trigger's copies land on the stack above the underlying spell, so if that instant or sorcery gets countered or fizzles first, the copies find no legal target and fizzle in turn. Zero commander casts leaves you a four-mana Twincast, the target resolving twice; three casts yields three copies of Fury Storm, and with the original that's four copies of the target spell plus the underlying spell itself for five resolutions.