Overlord of the Balemurk

Impending 5—{1}{B} (If you cast this spell for its impending cost, it enters with five time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.)
Whenever this permanent enters or attacks, mill four cards, then you may return a non-Avatar creature card or a planeswalker card from your graveyard to your hand.

Popular Egotist

{1}{B}, Sacrifice another creature or enchantment: This creature gains indestructible until end of turn. Tap it. (Damage and effects that say "destroy" don't destroy it.)
Whenever you sacrifice a permanent, target opponent loses 1 life and you gain 1 life.

Resurrected Cultist

Delirium — {2}{B}{B}: Return this card from your graveyard to the battlefield with a finality counter on it. Activate only if there are four or more card types among cards in your graveyard and only as a sorcery. (If a creature with a finality counter on it would die, exile it instead.)

Spectral Snatcher

Ward—Discard a card. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Sporogenic Infection

Enchant creature
When this Aura enters, target player sacrifices a creature of their choice other than enchanted creature.
When enchanted creature is dealt damage, destroy it.

Demon

Unholy Annex // Ritual Chamber

Unholy Annex

At the beginning of your end step, draw a card. If you control a Demon, each opponent loses 2 life and you gain 2 life. Otherwise, you lose 2 life.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Ritual Chamber

When you unlock this door, create a 6/6 black Demon creature token with flying.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Unstoppable Slasher

Deathtouch
Whenever this creature deals combat damage to a player, they lose half their life, rounded up.
When this creature dies, if it had no counters on it, return it to the battlefield tapped under its owner's control with two stun counters on it.

Friendly Ghost

Flying
When this creature enters, target creature gets +2/+4 until end of turn.

Valgavoth, Terror Eater

Flying, lifelink
Ward—Sacrifice three nonland permanents.
If a card you didn't control would be put into an opponent's graveyard from anywhere, exile it instead.
During your turn, you may play cards exiled with Valgavoth. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.

Valgavoth's Faithful

{3}{B}, Sacrifice this creature: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Vile Mutilator

As an additional cost to cast this spell, sacrifice a creature or enchantment.
Flying, trample
When this creature enters, each opponent sacrifices a nontoken enchantment of their choice, then sacrifices a nontoken creature of their choice.

Winter's Intervention

Winter's Intervention deals 2 damage to target creature. You gain 2 life.

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Bedhead Beastie

Menace (This creature can't be blocked except by two or more creatures.)
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Betrayer's Bargain

As an additional cost to cast this spell, sacrifice a creature or enchantment or pay {2}.
Betrayer's Bargain deals 5 damage to target creature. If that creature would die this turn, exile it instead.

Boilerbilges Ripper

When this creature enters, you may sacrifice another creature or enchantment. When you do, this creature deals 2 damage to any target.

Duskmourn: House of Horror