Gonti's Aether Heart

Extra turns have always been the most policed effect in the game, and the designers' favorite leash is a hard mana wall plus a one-shot clause. This is the energy-economy version of that bargain. The eight energy you spend on the extra-turn ability is a cost you pay, but it is one you build toward rather than budget for: two counters at a time, off this artifact when it lands and off every other artifact you control that follows it. That reframes the whole proposition. The card is not a Time Warp you cast; it is a meter you fill, and how fast it fills is a direct function of how artifact-dense your deck is once the six mana is spent and the Heart is on the battlefield. The exile-on-activation is the safety valve, ensuring the turn comes once rather than looping, and it also imposes a real deadline: the Heart is the source of the energy trigger, so the moment you cash it in, the meter stops. Everything you were going to bank has to be banked before you pull the trigger. Play out a steady drip of cheap artifacts after it resolves and eight counters arrive faster than the sticker cost suggests, which is the trick: the front-end price is mana, the back-end price is a board you were assembling anyway. It belongs to the small family of permanents that turned energy from a flavor counter into a genuine sub-economy, and it is the most decadent thing that economy was ever asked to buy.