Piranha Fly

Peculiar Lighthouse

Peculiar Lighthouse enters tapped unless a player has 13 or less life.
{T}: Add {U} or {R}.

Resurrected Cultist

Delirium — {2}{B}{B}: Return Resurrected Cultist 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.)

Enduring Curiosity

Flash
Whenever a creature you control deals combat damage to a player, draw a card.
When Enduring Curiosity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Valgavoth's Faithful

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

Widow's Walk

(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.)
Whenever a creature you control attacks alone, it gets +1/+0 and gains deathtouch until end of turn.

Derelict Attic

(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.)
When you unlock this door, you draw two cards and you lose 2 life.

Derelict Attic // Widow's Walk

Raucous Carnival

Raucous Carnival enters tapped unless a player has 13 or less life.
{T}: Add {R} or {W}.

Dissection Tools

When Dissection Tools enters, manifest dread, then attach Dissection Tools to that creature.
Equipped creature gets +2/+2 and has deathtouch and lifelink.
Equip—Sacrifice a creature.

Erratic Apparition

Flying, vigilance
Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, Erratic Apparition gets +1/+1 until end of turn.

Unnerving Grasp

Return up to one target nonland permanent to its owner's hand. Manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)

Fear of Isolation

As an additional cost to cast this spell, return a permanent you control to its owner's hand.
Flying

Swamp

Island

Unstoppable Slasher

Deathtouch
Whenever Unstoppable Slasher deals combat damage to a player, they lose half their life, rounded up.
When Unstoppable Slasher 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.

Paranormal Analyst

Whenever you manifest dread, put a card you put into your graveyard this way into your hand.

Ritual Chamber

(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.)
When you unlock this door, create a 6/6 black Demon creature token with flying.

Unholy Annex

(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.)
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.

Unholy Annex // Ritual Chamber

Vanish from Sight

Target nonland permanent's owner puts it on the top or bottom of their library. Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Murder

Winter's Intervention

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

Fear of Failed Tests

Whenever Fear of Failed Tests deals combat damage to a player, draw that many cards.

Sporogenic Infection

Enchant creature
When Sporogenic Infection enters, target player sacrifices a creature other than enchanted creature.
When enchanted creature is dealt damage, destroy it.

Floodpits Drowner

Flash
Vigilance
When Floodpits Drowner enters, tap target creature an opponent controls and put a stun counter on it.
{1}{U}, {T}: Shuffle Floodpits Drowner and target creature with a stun counter on it into their owners' libraries.