Twinning Staff

Copy effects usually stack multiplicatively, but this one operates on the arithmetic underneath every copy trigger: whatever number of copies a spell or ability would make, it adds one more. Fork a spell and you get two copies instead of one; the plus-one is deliberately additive rather than doubling, which keeps a single copy effect from spiraling on its own while letting a high-count copy engine tip lopsided. Point it at something that already copies generously, where each trigger produces many instances, and one extra copy per trigger compounds fast. The choice-of-new-targets clause matters as much as the count: the bonus copy is not locked to the original's targets, so a spell aimed at one creature can have its extra instance redirected elsewhere, widening reach rather than just stacking the same effect. The activated ability is a fallback for decks that want a copy engine without dedicating spell slots to one: seven mana and a tap to duplicate any instant or sorcery you control, again with fresh targets on offer. That price is steep enough to be a late-game luxury rather than the reason to run the card; the passive replacement effect is the real draw. As a colorless artifact, it slots into any copy-focused shell regardless of what colors are generating the copies, which is the quiet argument for it well outside the blue-red spells decks that first come to mind.