Panoptic Mirror

Free spells with a tax, paid once up front and collected every turn thereafter. The imprint mechanic here is a deferred-cost engine: you pay X plus the activation to lock a spell into exile, then each upkeep the artifact offers to mint a fresh copy and cast it for nothing. Crucially, the imprinted card is never spent; it stays exiled and gets copied rather than consumed, which makes this a true repeating loop rather than a one-shot recursion outlet. The design tension is entirely in the front-loaded math: paying full mana value to imprint a Time Walk or a tutor means a slow, telegraphed setup, but the payoff compounds because every subsequent turn is pure profit. The cleanest abuse is imprinting an extra-turn spell, then taking unbounded turns as the upkeep trigger fires before you ever pass priority. Wizards built a card whose ceiling is "do this spell again, forever, for free," and the brake is thin: the upkeep trigger is a may, you have to survive the gap between activations, and the imprint activation carries no timing restriction, so you can load the engine at instant speed during an opponent's turn and collect on your own upkeep. It reads like a combo piece written in plain English, the kind of artifact that looks fair until you notice nothing about it cares whether the copied spell was ever meant to be repeatable.