Interestingly enough, this can work on any Xyz monster, but its usually used to keep the Zoodiac combos going
Here you have a two mana body that shuts it all down
If you don't control an Army, create a 0/0 black Orc Army creature token first.) Creature - Beast Witch-king of Angmar Flying Whenever one or more creatures deal combat damage to you, each opponent sacrifices a creature of their choice that dealt combat damage to you this turn
In fact, the non-creature versions of these effects are usually more resilient, since they can't be picked off by creature removal
I also really enjoy this card for Type Four where it's heavy Black mana cost won't matter since you have infinite mana and it's a bit easier to cast in Commander than other casual formats with its Arcane Signets, Command Towers and Commander's Spheres effects
Self-mill commanders aid this strategy in one of two ways: They mill you, or they care about when you mill or have a bunch of cards (often creatures) in the graveyard