Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Abzan Advantage

Target player sacrifices an enchantment. Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Altar's Reap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Alseid of Life's Bounty

Lifelink
{1}, Sacrifice Alseid of Life's Bounty: Target creature or enchantment you control gains protection from the color of your choice until end of turn.

Abyssal Gatekeeper

When Abyssal Gatekeeper dies, each player sacrifices a creature.

Agent of the Fates

Deathtouch
Heroic — Whenever you cast a spell that targets Agent of the Fates, each opponent sacrifices a creature.

Athreos, Shroud-Veiled

Indestructible
As long as your devotion to white and black is less than seven, Athreos isn't a creature.
At the beginning of your end step, put a coin counter on another target creature.
Whenever a creature with a coin counter on it dies or is put into exile, return that card to the battlefield under your control.