Some of the best cards in Magic: The Gathering involve sacrificing your own creatures to reap bigger rewards
That being said, the top-level pitch for Tarkir was established well before the release of Murders at Karlov Manor and remained the same throughout development
The remainder of the list looks to generate extra wraiths the Nazgl can pump up, and theres plenty of card draw and protection to keep the wheels turning and your legion of monstrosities expanding
Walker benefits from a sac outlet so that you can generate fliers as and when you need them
however, its usefulness is highly dependent on the quality and timing of the bosses events, making it inconsistent and situational, so in most traditional Magic formats it would be weaker than flexible, self-directed copy effects like **Reverberate**, **Twincast**, or **Lithoform Engine**, which let you copy your own or opponents impactful spells on demand
Bolass Citadel (282k decks, Game Changer, $50) If youve never played with or against this in Commander, just know that its a worthy Tinker target in Vintage Cube, and thats a format with only 20 life