Demon's Herald

Build-around bait of the most demanding kind: a fragile one-drop whose entire purpose is to assemble a Grixis sacrifice and reach for one specific creature, Prince of Thralls. The activation reads like a Johnny puzzle box: spend three more mana, tap, and feed it a blue creature, a black creature, and a red creature all at once, and your library yields the payoff straight to the battlefield. The tutor-to-battlefield clause is the strong half of the bargain (no casting cost paid, no counterspell window on the creature itself), but the toll to pull it carries two distinct hurdles. The first is staging three differently-colored bodies you are willing to sacrifice on the same turn; the second is the search restriction, which reaches only into your library. A Prince of Thralls stranded in hand, dumped in the graveyard, or exiled is invisible to the Herald, so the deck has to keep its single payoff buried in the deck until the moment arrives. This belongs to a tradition of named-card enablers that exist solely to fetch one marquee target, the kind of one-to-one engine that lives or dies on whether that target justifies the contortion. Outside a deck expressly assembled to do exactly this, the activation is dead weight stapled to a Human Wizard; inside one, it is the lever. The Herald never pretended to be anything else.