Blood Bairn

A free sacrifice outlet stapled to a body, which is the part that matters more than the +2/+2 it hands out. The pump is the lure; the engine is that you can convert any creature into a sacrifice trigger at no mana cost, at instant speed, as many times as you have fodder. That makes it a quiet workhorse for any deck built on death triggers, undying counters, or graveyard recursion: feed it a creature that wants to die and the body it leaves behind is incidental. The cost discipline is built into the outlet itself, since it can only eat another creature, never itself, so it cannot fizzle its own value loop down to a single permanent. Aristocrats decks have always needed an outlet that asks for nothing but a creature, and this is one of the cleanest versions of that template: no payment, no tap, no per-turn cap. The vampire flavor of growing on spilled blood is the surface reading, but structurally this is plumbing. The +2/+2 is what you point to when you have nothing better to sacrifice into; the repeatable, mana-free sac itself is why the card keeps showing up wherever creatures are meant to die on purpose.