Whenever Witch-king attacks, defending player sacrifices a creature with the least power among creatures they control.
Witch-king is a mono-black evasive beater that grinds down boards by forcing each defending player to sacrifice their weakest creature whenever it attacks. You play a midrange-to-control game: ramp into the commander, protect it, swing every turn to strip blockers and chip life, then close with reanimation, drain, or a big finisher. The edict-on-attack synergizes with token swarms and ping effects that shrink opposing creatures into easy sacrifice fodder.
Repeatable, free creature removal every combat that ignores hexproof/indestructible/protection
Flying evasion makes it hard to block and reliably gets the trigger online
Mono-black gives access to the best tutors, reanimation, and drain in the format
Punishes go-wide token decks and pillow-fort defenders by eating their chumps
Forces sacrifice even when you can't kill the targeted creature in combat
The edict only hits the lowest-power creature, so it whiffs against players hoarding tokens or weenies you'd rather not let them keep
Removal-light board states let opponents keep their key threats while sacrificing junk
Single big threat strategy is vulnerable to spot removal and board wipes
No built-in card advantage or protection on the commander itself
Six mana means it can come down late against fast combo decks