Ashnod's Altar

Gisela, the Broken Blade

Flying, first strike, lifelink
At the beginning of your end step, if you both own and control Gisela, the Broken Blade and a creature named Bruna, the Fading Light, exile them, then meld them into Brisela, Voice of Nightmares.

Overseer of the Damned

Flying
When Overseer of the Damned enters, you may destroy target creature.
Whenever a nontoken creature an opponent controls dies, create a tapped 2/2 black Zombie creature token.

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

Bloodflow Connoisseur

Sacrifice a creature: Put a +1/+1 counter on Bloodflow Connoisseur.

Bloodthrone Vampire

Sacrifice a creature: Bloodthrone Vampire gets +2/+2 until end of turn.

Martyr's Bond

Whenever Martyr's Bond or another nonland permanent you control is put into a graveyard from the battlefield, each opponent sacrifices a permanent of their choice that shares a card type with it.