Grim Bauble

Removal that leaves something behind is a rare thing in black, and this is that: a one-mana artifact that shrinks an opposing creature the moment it lands, then lingers on the battlefield as a spare part until you have the mana to cash it in. The -2/-2 on entry does the immediate work, killing X/2s and smaller outright or ganging up with combat to finish something larger, but the design's real trick is decoupling that kill from the artifact's second life. Because the removal is stapled to a permanent rather than an instant, the card feeds anything that counts artifacts or rewards their arrival, and it can enter more than once if something returns it. The sacrifice mode turns the used-up husk into card selection rather than a dead draw (Surveil 2, so you decide how much fuel to bin and in what order). A cheap answer that would ordinarily leave you a card down instead leaves an artifact behind, and that artifact converts into digging and self-mill on your own schedule. The -2/-2 is priced as a fragile early answer rather than a catch-all; against a three-toughness body it does not kill on the way in, only shrinks it for a turn, which is what keeps a one-mana permanent from reading as unconditional removal. The whole shape of the card is that two-beat rhythm: the strike now, the surveil whenever the mana comes free.