Rite of Consumption

As an additional cost to cast this spell, sacrifice a creature.
Rite of Consumption deals damage equal to the sacrificed creature's power to target player or planeswalker. You gain life equal to the damage dealt this way.

Livaan, Cultist of Tiamat

Whenever you cast a noncreature spell, target creature gets +X/+0 until end of turn, where X is that spell's mana value.
Choose a Background (You can have a Background as a second commander.)

Blood Rites

{1}{R}, Sacrifice a creature: Blood Rites deals 2 damage to any target.

Cult of the Waxing Moon

Whenever a permanent you control transforms into a non-Human creature, create a 2/2 green Wolf creature token.

Novice Occultist

When Novice Occultist dies, you draw a card and you lose 1 life.

Rakdos Riteknife

Equipped creature gets +1/+0 for each blood counter on Rakdos Riteknife and has "{T}, Sacrifice a creature: Put a blood counter on Rakdos Riteknife."
{B}{R}, Sacrifice Rakdos Riteknife: Target player sacrifices a permanent for each blood counter on Rakdos Riteknife.
Equip {2}

Awoken Demon

Ecstatic Awakener

{2}{B}, Sacrifice another creature: Draw a card, then transform Ecstatic Awakener. Activate only once each turn.

Ecstatic Awakener // Awoken Demon

Swamp

Pyretic Ritual

Dark Ritual

Deathrite Shaman

{T}: Exile target land card from a graveyard. Add one mana of any color.
{B}, {T}: Exile target instant or sorcery card from a graveyard. Each opponent loses 2 life.
{G}, {T}: Exile target creature card from a graveyard. You gain 2 life.

Agadeem Occultist

{T}: Put target creature card from an opponent's graveyard onto the battlefield under your control if its mana value is less than or equal to the number of Allies you control.

Deathcult Rogue

Deathcult Rogue can't be blocked except by Rogues.

Westvale Cult Leader

Westvale Cult Leader's power and toughness are each equal to the number of creatures you control.
At the beginning of your end step, create a 1/1 white and black Human Cleric creature token.

Hanweir Militia Captain

At the beginning of your upkeep, if you control four or more creatures, transform Hanweir Militia Captain.

Hanweir Militia Captain // Westvale Cult Leader

Death Cultist

Sacrifice Death Cultist: Target player loses 1 life and you gain 1 life.

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Hagra Diabolist

Whenever Hagra Diabolist or another Ally enters the battlefield under your control, you may have target player lose life equal to the number of Allies you control.

Altar of Shadows

At the beginning of your precombat main phase, add {B} for each charge counter on Altar of Shadows.
{7}, {T}: Destroy target creature. Then put a charge counter on Altar of Shadows.

Grisly Ritual

Destroy target creature or planeswalker. Create two Blood tokens. (They're artifacts with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Forbidden Ritual

Sacrifice a nontoken permanent. If you do, target opponent loses 2 life unless that player sacrifices a permanent or discards a card. You may repeat this process any number of times.

Cult Guildmage

{3}{B}, {T}: Target player discards a card. Activate only as a sorcery.
{R}, {T}: Cult Guildmage deals 1 damage to target opponent or planeswalker.

Malefic Scythe

Malefic Scythe enters the battlefield with a soul counter on it.
Equipped creature gets +1/+1 for each soul counter on Malefic Scythe.
Whenever equipped creature dies, put a soul counter on Malefic Scythe.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Occult Epiphany

Draw X cards, then discard X cards. Create a 1/1 white Spirit creature token with flying for each card type among cards discarded this way.

Bloodrite Invoker

{8}: Target player loses 3 life and you gain 3 life.

Selhoff Occultist

Whenever Selhoff Occultist or another creature dies, target player mills a card.

Bone Offering

Create a tapped 4/1 black Skeleton creature token with menace. (Then exile this card. You may cast the artifact later from exile.)

Altar of Bhaal

{2}{B}, {T}, Exile a creature you control: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Altar of Bhaal // Bone Offering

Carnage Altar

Inalla, Archmage Ritualist

Eminence — Whenever another nontoken Wizard enters the battlefield under your control, if Inalla, Archmage Ritualist is in the command zone or on the battlefield, you may pay {1}. If you do, create a token that's a copy of that Wizard. The token gains haste. Exile it at the beginning of the next end step.
Tap five untapped Wizards you control: Target player loses 7 life.

Stromkirk Occultist

Trample
Whenever Stromkirk Occultist deals combat damage to a player, exile the top card of your library. Until end of turn, you may play that card.
Madness {1}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Ritual of Soot

Destroy all creatures with mana value 3 or less.

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 creature deals 6 damage to you."

Orbs of Warding

You have hexproof. (You can't be the target of spells or abilities your opponents control.)
If a creature would deal damage to you, prevent 1 of that damage.

Priest of the Blood Rite

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

Oni-Cult Anvil

Whenever one or more artifacts you control leave the battlefield during your turn, create a 1/1 colorless Construct artifact creature token. This ability triggers only once each turn.
{T}, Sacrifice an artifact: Oni-Cult Anvil deals 1 damage to each opponent. You gain 1 life.

Cultist's Staff

Equipped creature gets +2/+2.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Leshrac's Rite

Enchant creature
Enchanted creature has swampwalk. (It can't be blocked as long as defending player controls a Swamp.)

Razaketh's Rite

Search your library for a card, put that card into your hand, then shuffle.
Cycling {B} ({B}, Discard this card: Draw a card.)

Scion of Halaster

Commander creatures you own have "The first time you would draw a card each turn, instead look at the top two cards of your library. Put one of them into your graveyard and the other back on top of your library. Then draw a card."

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.)

Earth-Cult Elemental

Siege Monster — When Earth-Cult Elemental enters the battlefield, roll a d20.
1—9 | Each player sacrifices a permanent.
10—19 | Each opponent sacrifices a permanent.
20 | Each opponent sacrifices two permanents.

Inherited Fiend

Flying
{2}{B}: Exile target creature card from a graveyard. Put a +1/+1 counter on Inherited Fiend.

Heirloom Mirror

{1}, {T}, Pay 1 life, Discard a card: Draw a card, mill a card, then put a ritual counter on Heirloom Mirror. Then if it has three or more ritual counters on it, remove them and transform it. Activate only as a sorcery.

Heirloom Mirror // Inherited Fiend

Cultist of the Absolute

Commander creatures you own get +3/+3 and have flying, deathtouch, "Ward—Pay 3 life," and "At the beginning of your upkeep, sacrifice a creature."

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

Rite of Ruin

Choose an order for artifacts, creatures, and lands. Each player sacrifices one permanent of the first type, sacrifices two of the second type, then sacrifices three of the third type.

Kill-Suit Cultist

Kill-Suit Cultist attacks each combat if able.
{B}, Sacrifice Kill-Suit Cultist: The next time damage would be dealt to target creature this turn, destroy that creature instead.

Archfiend's Vessel

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When Archfiend's Vessel enters the battlefield, if it entered from your graveyard or you cast it from your graveyard, exile it. If you do, create a 5/5 black Demon creature token with flying.

Midnight Ritual

Exile X target creature cards from your graveyard. For each creature card exiled this way, create a 2/2 black Zombie creature token.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Exultant Cultist

Bloodhusk Ritualist

Multikicker {B} (You may pay an additional {B} any number of times as you cast this spell.)
When Bloodhusk Ritualist enters the battlefield, target opponent discards a card for each time it was kicked.

Rite of the Raging Storm

Creatures named Lightning Rager can't attack you or planeswalkers you control.
At the beginning of each player's upkeep, that player creates a 5/1 red Elemental creature token named Lightning Rager. It has trample, haste, and "At the beginning of the end step, sacrifice this creature."

Ritual of the Returned

Exile target creature card from your graveyard. Create a black Zombie creature token. Its power is equal to that card's power and its toughness is equal to that card's toughness.

Dragon Cultist

Commander creatures you own have "At the beginning of your end step, if a source you controlled dealt 5 or more damage this turn, create a 4/4 red Dragon creature token with flying."

Scarscale Ritual

As an additional cost to cast this spell, put a -1/-1 counter on a creature you control.
Draw two cards.

Soulreaper of Mogis

{2}{B}, Sacrifice a creature: Draw a card.

Creeping Inn

Whenever Creeping Inn attacks, you may exile a creature card from your graveyard. If you do, each opponent loses X life and you gain X life, where X is the number of creature cards exiled with Creeping Inn.
{4}: Creeping Inn phases out.

Hostile Hostel

{T}: Add {C}.
{1}, {T}, Sacrifice a creature: Put a soul counter on Hostile Hostel. Then if there are three or more soul counters on it, remove those counters, transform it, then untap it. Activate only as a sorcery.

Hostile Hostel // Creeping Inn

Snake Cult Initiation

Enchant creature
Enchanted creature has poisonous 3. (Whenever it deals combat damage to a player, that player gets three poison counters. A player with ten or more poison counters loses the game.)

Rite of Oblivion

As an additional cost to cast this spell, sacrifice a nonland permanent.
Exile target nonland permanent.
Flashback {2}{W}{B} (You may cast this card from your graveyard for its flashback cost and any additional costs. Then exile it.)

Cultbrand Cinder

When Cultbrand Cinder enters the battlefield, put a -1/-1 counter on target creature.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Slaughter-Priest of Mogis

Whenever you sacrifice a permanent, Slaughter-Priest of Mogis gets +2/+0 until end of turn.
{2}, Sacrifice another creature or an enchantment: Slaughter-Priest of Mogis gains first strike until end of turn.

Blood Cultist

{T}: Blood Cultist deals 1 damage to target creature.
Whenever a creature dealt damage by Blood Cultist this turn dies, put a +1/+1 counter on Blood Cultist.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Bloodsoaked Altar

{T}, Pay 2 life, Discard a card, Sacrifice a creature: Create a 5/5 black Demon creature token with flying. Activate only as a sorcery.

Air-Cult Elemental

Flying
Whirlwind — When Air-Cult Elemental enters the battlefield, return up to one other target creature to its owner's hand.