Glacian, Powerstone Engineer

Set the depth of the dig yourself, and pay for it in a currency most artifact engines want back: taps. Tapping X untapped artifacts looks at that many cards, keeps one, and buries the rest, which sounds like pure filtering until you notice the artifact you would spend on this is the same artifact you would spend for mana. A Signet used to cast a spell is already tapped; it cannot then feed the ability that turn. So every activation is a negotiation between building your mana and refining your draws, and the deeper you reach, the more of your library goes to the graveyard for the one card you take. That library-to-graveyard clause is not a tax to route around but a resource to redirect: pointed at reanimation or graveyard payoffs, seeding the yard becomes a reason to reach deeper rather than a cost to minimize. Partner lets this engine sit beside a second commander who cashes in what it unearths. At 3/6, it arrives long after the opening turns are settled, and the generous toughness does the unglamorous work of keeping the artificer alive on the board while the artifact count climbs and each activation gets wider. Think of it as a piston that only turns over once the machine around it is already running: a late, compounding engine for a board already thick with metal.