Barrels of Blasting Jelly

A one-mana rock that begins as color fixing and later spends itself as a delayed-fuse removal spell. The design tension is economic. The first ability doesn't net mana: you pay one to get one, so it filters colors rather than accelerating you, and the once-each-turn clause keeps it from ever spiking into a burst-mana engine the way an untapped ritual would. The second ability asks for five mana plus the tap plus the artifact itself to deal a fixed five damage. That is a steep total for a single point of removal, but you rarely pay it cold. The barrels sit on the battlefield smoothing your colors across the early turns, and only later (once the mana is flowing and a threat needs answering) do they convert into a sacrifice-fueled blast. It is a mana source that carries its own exit clause: the same permanent that helped cast your spells becomes the spell that clears the blocker in front of your finisher. Fixing artifacts that also threaten to do something offensive are an old idea, but most either fix or fight. Folding both into a single one-drop is the wrinkle, and the timing does the balancing: you get the color access for as many turns as you leave the barrels alone, then trade all of it for five damage the moment you crack them. The card is one long decision about when to stop fixing and start shooting.