Manifest Dread

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.)

Monstrous Emergence

As an additional cost to cast this spell, choose a creature you control or reveal a creature card from your hand.
Monstrous Emergence deals damage equal to the power of the creature you chose or the card you revealed to target creature.

Grasping Longneck

Reach
When Grasping Longneck dies, you gain 2 life.

Spineseeker Centipede

When Spineseeker Centipede enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Delirium — Spineseeker Centipede gets +1/+2 and has vigilance as long as there are four or more card types among cards in your graveyard.

Fear of Lost Teeth

When Fear of Lost Teeth dies, it deals 1 damage to any target and you gain 1 life.

Swamp

Break Down the Door

Choose one —
• Exile target artifact.
• Exile target enchantment.
• 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.)

Forest

Wary Watchdog

When Wary Watchdog enters or dies, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Dashing Bloodsucker

Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, Dashing Bloodsucker gets +2/+0 and gains lifelink until end of turn.

Coordinated Clobbering

Tap one or two target untapped creatures you control. They each deal damage equal to their power to target creature an opponent controls.

Cautious Survivor

Survival — At the beginning of your second main phase, if Cautious Survivor is tapped, you gain 2 life.

Commune with Evil

Look at the top four cards of your library. Put one of them into your hand and the rest into your graveyard. You gain 3 life.

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 Overlord of the Balemurk 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.

Flesh Burrower

Deathtouch
Whenever Flesh Burrower attacks, another target creature you control gains deathtouch until end of turn.

Murder

Fanatic of the Harrowing

When Fanatic of the Harrowing enters, each player discards a card. If you discarded a card this way, draw a card.

Killer's Mask

When Killer's Mask enters, manifest dread, then attach Killer's Mask to that creature. (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.)
Equipped creature has menace.
Equip {2}

Overgrown Zealot

{T}: Add one mana of any color.
{T}: Add two mana of any one color. Spend this mana only to turn permanents face up.

Appendage Amalgam

Flash
Whenever Appendage Amalgam attacks, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Fear of the Dark

Whenever Fear of the Dark attacks, if defending player controls no Glimmer creatures, it gains menace and deathtouch until end of turn. (A creature with menace can't be blocked except by two or more creatures.)

Valgavoth's Onslaught

Manifest dread X times, then put X +1/+1 counters on each of those creatures. (To manifest dread, look at the top two cards of your library, then 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.)