Vile Deacon

Whenever Vile Deacon attacks, it gets +X/+X until end of turn, where X is the number of Clerics on the battlefield.

Dark Ritual

Diabolic Edict

Night's Whisper

Profane Prayers

Profane Prayers deals X damage to any target and you gain X life, where X is the number of Clerics on the battlefield.

Whipgrass Entangler

{1}{W}: Until end of turn, target creature gains "This creature can't attack or block unless its controller pays {1} for each Cleric on the battlefield."

Lady Orca

Demonic Stench

Each creature that blocked this turn gets -1/-1 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Hezrou

Whenever one or more creatures you control become blocked, each blocking creature gets -1/-1 until end of turn.

Hezrou // Demonic Stench

Swamp

Mortician Beetle

Whenever a player sacrifices a creature, you may put a +1/+1 counter on Mortician Beetle.

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.