Altar of Dementia

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

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Destroy target creature.

Shadowborn Apostle

A deck can have any number of cards named Shadowborn Apostle.
{B}, Sacrifice six creatures named Shadowborn Apostle: Search your library for a Demon creature card, put it onto the battlefield, then shuffle.

Altar of the Pantheon

Your devotion to each color and each combination of colors is increased by one.
{T}: Add one mana of any color. If you control a God, a Demigod, or a legendary enchantment, you gain 1 life.

Netherborn Altar

{T}, Put a soul counter on Netherborn Altar: Put your commander into your hand from the command zone. Then you lose 3 life for each soul counter on Netherborn Altar.

Priest of Forgotten Gods

{T}, Sacrifice two other creatures: Any number of target players each lose 2 life and sacrifice a creature of their choice. You add {B}{B} and draw a card.

Containment Priest

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

Priest of Fell Rites

{T}, Pay 3 life, Sacrifice Priest of Fell Rites: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.
Unearth {3}{W}{B} ({3}{W}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Carnage Altar

Selfless Cathar

{1}{W}, Sacrifice Selfless Cathar: Creatures you control get +1/+1 until end of turn.

Village Cannibals

Whenever another Human creature dies, put a +1/+1 counter on Village Cannibals.

Shadow-Rite Priest

Other Clerics you control get +1/+1.
{3}{B}{B}, {T}, Sacrifice another Cleric: Search your library for a black creature card, put it onto the battlefield, then shuffle.

Village Rites

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

Avacynian Priest

Athreos, God of Passage

Indestructible
As long as your devotion to white and black is less than seven, Athreos isn't a creature.
Whenever another creature you own dies, return it to your hand unless target opponent pays 3 life.

Unruly Mob

Whenever another creature you control dies, put a +1/+1 counter on Unruly Mob.

Cathar Commando

Flash (You may cast this spell any time you could cast an instant.)
{1}, Sacrifice this creature: Destroy target artifact or enchantment.