Furnace Skullbomb

Crack it for a card whenever the topdeck matters more than the object sitting on the battlefield, and you have exactly the cheap, self-replacing artifact that costs nothing to include over an ordinary cantrip. That is the floor: one mana to deploy, one to sacrifice for a fresh card, plus a countable artifact body for anything that cares about permanents you control. The red mode is what pulls it up a tier. For an extra red, cracking it dumps two oil counters onto a creature or artifact you control before drawing, which converts a filler artifact into a fuel source: prime a counter-hungry creature, top off a charged permanent, or push an oil-counter payoff one activation closer, all while still cycling itself away. The sorcery-speed restriction on that mode is the balancing check; you cannot hold it up as a free instant-speed pump during an opponent's end step, so the counter placement demands you spend the tempo yourself while your own turn is open. It reads as a modest cog, and it is, but the design is precise about it: card draw, a persistent artifact presence, and a counter-placement effect all folded into a single one-mana object that never asks you to spend a card to run it.