Powder Keg

The dial is the whole point. The keg charges one fuse counter per upkeep, so its detonation hits a precise mana value rather than the whole board: you set the number in advance and pop it to clear a swarm of one-drops, a glut of two-drops, or a single overcosted threat while leaving your own curve untouched if you built around the count. That telegraphing is what lets a colorless, two-mana sweeper exist at all. It rewards the patient player who reads the board correctly and gives the impatient one a chance to play around the count they can see ticking up. With zero counters it can fire the turn it lands, blowing up token creatures and other mana-value-zero artifacts and creatures immediately; every higher number costs a turn of waiting. The keg even doubles as a deterrent on the battlefield, since an opponent staring at two counters thinks twice before deploying a third two-drop. The sacrifice clause is what prices the effect: each detonation is a one-shot, so the asymmetry has to be earned through sequencing rather than handed over for free. A single artifact that answers both creatures and artifacts in one activation, in any color, is the kind of deck-agnostic removal that travels anywhere, which is precisely why later designers revisited the shape, often trading the counter mechanic for a fixed number to lose the telegraph.