Dismember

Strip the life-payment clause off those two hybrid pips and what remains is an unremarkable black removal spell: -5/-5 for three mana, kills almost anything, asks nothing strange of you. The option to pay 2 life per pip instead of black mana is what changes who gets to cast it. An Affinity deck, a white aggro deck, a colorless artifact build: all of them can run premium creature removal off their life totals alone, and that portability is why the spell persists where most cheap kill spells stay locked behind their color. The price is real, though. Against the fast decks that most want a one-mana answer, four life is not free, and the spell scales its cost to your desperation; that tension is what stops it from being a costless splash. The -5/-5 framing matters as much as the casting cost: unlike a damage-based or destroy-based answer, it shrinks indestructible creatures out of existence and ignores damage-prevention shields, while leaving anything with six or more toughness standing. Phyrexian mana proved divisive enough that the design has been rationed carefully ever since, but this remains the clearest argument for what the mechanic was for: removing a color requirement without removing a real cost.