Scalding Cauldron

Preloading is the whole idea here, and the split cost is what makes it work: drop the artifact on a spare early turn, then sit on the three-mana activation as a colorless removal spell any deck can fire regardless of what its lands produce. All told it is a four-mana outlay spread across two turns to deal three damage, a rate nobody pays to trade with a single creature. What you buy for that steepness is deck-agnostic access. This is fixed removal that arrives in advance and waits, immune to counterspells once it is on the battlefield, castable off a manabase with no red source at all. That is the tension every colorless burn effect wrestles with: to hand the removal to every color, you strip it of color, and the mana discount red would give you has to be repaid somewhere. Here the payment is tempo, split into an early down-payment and a delayed activation, plus the artifact-shaped window between casting and firing in which an opponent can strip it away with artifact removal. The three-damage ceiling keeps it inside the range of most small threats without touching anything larger. Because the sacrifice is baked into the activation cost, the artifact heads to the graveyard when it fires, which leaves a permanent off the battlefield but a fresh artifact in the yard for anything that wants to recur or reuse it. A patient answer for a deck that would rather own removal it can always cast than removal that is efficient.