Dragonspark Reactor

Two mana buys a meter, not a payoff. Every artifact that hits the battlefield afterward (the token, the trinket, the cheap equipment, the Reactor itself) ticks the counter upward while you play out your normal game, and the number climbs where the opponent can see it but cannot easily touch it once it is set. The sacrifice is where the design earns its keep: it splits the stored count across two targets, hammering a player for the full total and clearing up to one creature for the same amount, so a stockpiled Reactor is reach and removal fused into a single activation. That dual-target shape is the reason artifact-heavy decks read it as a pressure valve rather than a raw finisher, a lethal figure the table has to respect long before you decide to pull the trigger. It also folds a familiar aristocrats problem (turning board width into damage) onto one card: no sacrifice outlet plus drain package required, since the counting and the burst live in the same object. Patient by construction, it sits on the board doing nothing visible until the meter is high enough, then converts a game's worth of small artifact plays into one explosive turn.