Abyssal Horror

Flying
When Abyssal Horror enters, target player discards two cards.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on Chasm Skulker.
When Chasm Skulker dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on Chasm Skulker. (They can't be blocked as long as defending player controls an Island.)

Scaretiller

Whenever Scaretiller becomes tapped, choose one —
• You may put a land card from your hand onto the battlefield tapped.
• Return target land card from your graveyard to the battlefield tapped.

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Consuming Aberration

Consuming Aberration's power and toughness are each equal to the number of cards in your opponents' graveyards.
Whenever you cast a spell, each opponent reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Leeching Lurker

Lifelink
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Curse of Leeches

Enchant player
As this permanent transforms into Curse of Leeches, attach it to a player.
At the beginning of enchanted player's upkeep, they lose 1 life and you gain 1 life.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Curse of Leeches // Leeching Lurker

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Birthing Boughs

{4}, {T}: Create a 2/2 colorless Shapeshifter creature token with changeling. (It has every creature type.)

Urza's Incubator

As Urza's Incubator enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Abomination of Llanowar

Vigilance; menace (This creature can't be blocked except by two or more creatures.)
Abomination of Llanowar's power and toughness are each equal to the number of Elves you control plus the number of Elf cards in your graveyard.

Scorn Effigy

Foretell {0} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Arcane Adaptation

As Arcane Adaptation enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Nightmare Unmaking

Choose one —
• Exile each creature with power greater than the number of cards in your hand.
• Exile each creature with power less than the number of cards in your hand.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Yarok, the Desecrated

Deathtouch, lifelink
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Scarecrone

{1}, Sacrifice a Scarecrow: Draw a card.
{4}, {T}: Return target artifact creature card from your graveyard to the battlefield.

Conspiracy

As Conspiracy enters, choose a creature type.
Creatures you control are the chosen type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Ashiok, Nightmare Muse

+1: Create a 2/3 blue and black Nightmare creature token with "Whenever this creature attacks or blocks, each opponent exiles the top two cards of their library."
−3: Return target nonland permanent to its owner's hand, then that player exiles a card from their hand.
−7: You may cast up to three spells from among face-up cards your opponents own from exile without paying their mana costs.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Nightmare Shepherd

Flying
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that creature, except it's 1/1 and it's a Nightmare in addition to its other types.

Scrounged Scythe

Equipped creature gets +1/+1.
As long as equipped creature is a Human, it has menace. (It can't be blocked except by two or more creatures.)
Equip {2}

Harvest Hand

When Harvest Hand dies, return it to the battlefield transformed under your control.

Harvest Hand // Scrounged Scythe

Atraxa, Praetors' Voice

Flying, vigilance, deathtouch, lifelink
At the beginning of your end step, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Reaper King

({2/W} can be paid with any two mana or with {W}. This card's mana value is 10.)
Other Scarecrow creatures you control get +1/+1.
Whenever another Scarecrow you control enters, destroy target permanent.