Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Havoc Jester

Whenever you sacrifice a permanent, this creature deals 1 damage to any target.

Wayward Disciple

Whenever this creature or another creature you control dies, target opponent loses 1 life and you gain 1 life.

Pious Evangel

Whenever this creature or another creature you control enters, you gain 1 life.
{2}, {T}, Sacrifice another permanent: Transform this creature.

Pious Evangel // Wayward Disciple

Vile Deacon

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

Cleric

Whisper, Blood Liturgist

{T}, Sacrifice two creatures: Return target creature card from your graveyard to the battlefield.

Hellrider

Haste
Whenever a creature you control attacks, this creature deals 1 damage to the player or planeswalker it's attacking.

Priest of the Blood Rite

When this creature enters, create a 5/5 black Demon creature token with flying.
At the beginning of your upkeep, you lose 2 life.

Glistening Goremonger

When this creature dies, each opponent sacrifices an artifact or creature of their choice.

Pyretic Prankster

{3}{B/P}: Transform this creature. Activate only as a sorcery. ({B/P} can be paid with either {B} or 2 life.)

Pyretic Prankster // Glistening Goremonger

Tibalt, Rakish Instigator

Your opponents can't gain life.
−2: Create a 1/1 red Devil creature token with "When this token dies, it deals 1 damage to any target."

Raphael, Fiendish Savior

Flying
Other Demons, Devils, Imps, and Tieflings you control get +1/+1 and have lifelink.
At the beginning of each end step, if a creature card was put into your graveyard from anywhere this turn, create a 1/1 red Devil creature token with "When this token dies, it deals 1 damage to any target."

Lyzolda, the Blood Witch

{2}, Sacrifice a creature: Lyzolda deals 2 damage to any target if the sacrificed creature was red. Draw a card if the sacrificed creature was black.

Demon

Flying, trample
At the beginning of your upkeep, sacrifice another creature. If you can't, this creature deals 6 damage to you.

Rite of Belzenlok

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Create two 0/1 black Cleric creature tokens.
III — Create a 6/6 black Demon creature token with flying, trample, and "At the beginning of your upkeep, sacrifice another creature. If you can't, this token deals 6 damage to you."

Karlach, Fury of Avernus

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase.
Choose a Background (You can have a Background as a second commander.)

Demon's Disciple

When this creature enters, each player sacrifices a creature or planeswalker of their choice.

Scourge Devil

When this creature enters, creatures you control get +1/+0 until end of turn.
Unearth {2}{R} ({2}{R}: 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.)

Devil

When this creature dies, it deals 1 damage to any target.

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.