Flash

Ward {2}

Probing Telepathy -- Whenever a creature entering the battlefield under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.

{U}, {T}: Add {C}{C}{C}.

{T}: Add one mana of any color in your commander's color identity.

Flying, deathtouch

When Baleful Strix enters, draw a card.

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)

Equipped creature gets +X/+X, where X is the number of creature cards in all graveyards.

Equip {2}

Flying

At the beginning of your end step, exile the top card of each opponent's library. You may play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

Draw three cards, then put two cards from your hand on top of your library in any order.

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Horrors you control have menace.

Whenever a Horror you control deals combat damage to a player, that player mills that many cards.

At the beginning of your end step, choose target artifact or creature card in an opponent's graveyard that was put there from their library this turn. Put it onto the battlefield under your control.

Charcoal Diamond enters tapped.

{T}: Add {B}.

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.)

As Choked Estuary enters the battlefield, you may reveal an Island or Swamp card from your hand. If you don't, Choked Estuary enters the battlefield tapped.

{T}: Add {U} or {B}.

{T}: Add one mana of any color in your commander's color identity.

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Draw a card.

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.

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Whenever you tap a Swamp for mana, add an additional {B}.

Add {B}{B}{B}.

{1}, {T}: Add {U}{B}.

Menace

As an additional cost to cast black permanent spells, you may pay 2 life. Those spells cost {B} less to cast if you paid life this way. This effect reduces only the amount of black mana you pay.

Whenever you cast a black permanent spell, target creature you control gets +1/+1 and gains menace until end of turn.

{1}, {T}: Add {U}{B}.

Whenever a creature dealt damage by Dread Slaver this turn dies, return it to the battlefield under your control. That creature is a black Zombie in addition to its other colors and types.

Choose one --

• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.

• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Menace

Whenever Elder Brain attacks a player, exile all cards from that player's hand, then they draw that many cards. You may play lands and cast spells from among the exiled cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

Each player mills two cards. Then you put a creature card from a graveyard onto the battlefield under your control.

When Faceless Butcher enters the battlefield, exile target creature other than Faceless Butcher.

When Faceless Butcher leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Skulk (This creature can't be blocked by creatures with greater power.)

At the beginning of your upkeep, you may discard all the cards in your hand. If you do, draw that many cards.

When Geralf's Mindcrusher enters the battlefield, target player mills five cards.

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Destroy target nonartifact creature.

Whenever a creature you control becomes blocked, you may return it to its owner's hand.

Whenever one or more creatures you control deal combat damage to a player, draw a card.

Aberrant Tinkering -- When Grell Philosopher enters the battlefield and at the beginning of your upkeep, each Horror you control gains all activated abilities of target artifact an opponent controls until end of turn. You may spend blue mana as though it were mana of any color to activate those abilities.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Whenever Guiltfeeder attacks and isn't blocked, defending player loses 1 life for each card in their graveyard.

Commander creatures you own have "Whenever this creature becomes tapped, it and other creatures you control that share a creature type with it each get +2/+0 and gain undying until end of turn." (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Enchant creature

As long as enchanted creature is blue, it gets +1/+1 and has "Whenever this creature deals damage to an opponent, draw a card."

As long as enchanted creature is black, it gets +1/+1 and has "Whenever this creature deals damage to an opponent, that player discards a card."

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Flash

This spell can't be countered.

Whenever you cast a spell, choose up to one --

• Return target spell you don't control to its owner's hand.

• Return target nonland permanent to its owner's hand.

Destroy all creatures you don't control and all planeswalkers you don't control.

Devour Intellect -- When Intellect Devourer enters the battlefield, each opponent exiles a card from their hand until Intellect Devourer leaves the battlefield.

Body Thief -- You may play lands and cast spells from among cards exiled with Intellect Devourer. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

Hexproof

Whenever a creature card is put into an opponent's graveyard from anywhere, you may have Lazav, Dimir Mastermind become a copy of that card, except its name is Lazav, Dimir Mastermind, it's legendary in addition to its other types, and it has hexproof and this ability.

Kicker {3}{U}

Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

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.)

Whenever you attack with two or more creatures, draw a card.

Dominate Monster -- When Mind Flayer enters the battlefield, gain control of target creature for as long as you control Mind Flayer.

Whenever an opponent loses life, that player mills that many cards. (Damage causes loss of life.)

Whenever Nemesis of Reason attacks, defending player mills ten cards.

{T}: Add {C}.

{1}{U}{B}, {T}: Target player mills three cards.

Bestow {2}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)

Nighthowler and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.

Target player mills two cards. Draw two cards.

Look at the top three cards of your library, then put them back in any order. You may shuffle.

Draw a card.

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

This spell costs {2} less to cast if it targets a legendary creature.

Destroy target creature.

Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Whenever you draw a card, each opponent mills two cards.

Whenever a creature you control deals combat damage to a player, you may draw a card.

Cycling {2} ({2}, Discard this card: Draw a card.)

{T}: Add {C}.

{4}, {T}: Target creature can't be blocked this turn.

{X}, {T}: Target player mills X cards.

As Sewer Nemesis enters the battlefield, choose a player.

Sewer Nemesis's power and toughness are each equal to the number of cards in the chosen player's graveyard.

Whenever the chosen player casts a spell, that player mills a card.

Sky Diamond enters the battlefield tapped.

{T}: Add {U}.

Whenever Sludge Monster enters the battlefield or attacks, put a slime counter on up to one other target creature.

Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

{T}: Add {C}{C}.

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process.

{5}{U}: Draw a card, then discard a card.

({T}: Add {U} or {B}.)

Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

Equipped creature gets +2/+2 and has protection from green and from blue.

Whenever equipped creature deals combat damage to a player, you create a 2/2 green Wolf creature token and that player mills ten cards.

Equip {2}

{T}: Add {C}.

{T}: Add {U} or {B}. Activate only if you control a Swamp.

Defender

Thing in the Ice enters the battlefield with four ice counters on it.

Whenever you cast an instant or sorcery spell, remove an ice counter from Thing in the Ice. Then if it has no ice counters on it, transform it.

When this creature transforms into Awoken Horror, return all non-Horror creatures to their owners' hands.

Target player mills two cards.

Draw a card.

Whenever equipped creature attacks, defending player reveals cards from the top of their library until they reveal a land card. The creature gets +1/+0 until end of turn for each card revealed this way. That player puts the revealed cards into their graveyard.

Equip {2}

Uchuulon's power is equal to the number of Crabs, Oozes, and/or Horrors you control.

Horrific Symbiosis -- At the beginning of your end step, exile up to one target creature card from an opponent's graveyard. If you do, create a token that's a copy of Uchuulon.

Skulk (This creature can't be blocked by creatures with greater power.)

Whenever Wharf Infiltrator deals combat damage to a player, you may draw a card. If you do, discard a card.

Whenever you discard a creature card, you may pay {2}. If you do, create a 3/2 colorless Eldrazi Horror creature token.

Islandwalk, swampwalk (This creature can't be blocked as long as defending player controls an Island or a Swamp.)

Whenever Wrexial, the Risen Deep deals combat damage to a player, you may cast target instant or sorcery card from that player's graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Hive Mind -- Whenever a player mills one or more creature cards, you create a 1/1 black Horror creature token.

{1}, {T}: Target player mills three cards.

Choose a Background (You can have a Background as a second commander.)