Underhanded Designs

An enters-the-battlefield drain payoff rather than a death-trigger one: the wrinkle that defines it is that it cares about artifacts arriving, not leaving. That makes it the reward for the wide artifact deck, the one churning out cheap tokens and Servos and Thopters, where every body that hits the battlefield is a potential ping. The optional mana payment is the structural choice that keeps it from warping the curve: the drain is gated behind a tax, so each artifact entering forces a small decision about whether the one-point swing is worth the mana you had floating, rather than handing you free reach for simply playing your deck. The payoff scales with the number of permanents you can funnel through, but it never gets ahead of the mana you can spare. The sacrifice ability is the closer bolted onto the same chassis: once two or more artifacts are out, the enchantment cashes itself in for unconditional creature removal, giving the card a graceful exit when the drain has done its work or the board needs clearing. That second mode means the card is not merely an incremental-damage clock; it can sit and tick for most of a game, then convert into a kill spell at the exact moment one is needed. This is the black engine enchantment that asks you to assemble the synergy around it, and the two-artifact gate on the removal makes plain which kind of deck was meant to draw it up.