Pyromancer's Goggles

Most spell-copying lives on the spell itself or on a one-shot trigger; this files the copy on a mana rock, which is a quietly strange place to put it. The Goggles produce ordinary red mana like any other artifact, but the mana is marked: spend it on a red instant or sorcery, and the spell copies. That decoupling is the whole design idea. The copy clause does not care what you cast, only that the marked mana paid for it, so the card scales with whatever red instant or sorcery you point it at rather than capping out on a fixed effect. A burn spell doubles its damage; a draw spell doubles its cards; a sweeper hits twice with fresh targets. The new-targets clause turns even a single-target spell into a two-for-one. The tax is the rate (five generic for a rock that taps for one) and the timing: you need the Goggles down, untapped, and a payoff spell in hand on the same turn, which files it under build-around rather than value piece. The legendary line matters too, since it normally keeps you from controlling a second copy that could mark a second red mana toward the same spell for a stacked pair of triggers. It is a copy engine disguised as ramp, and the disguise is exactly what constrains the deck around it: to earn the artifact slot, the whole spell suite has to be worth doubling.