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.

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.

You draw a card at the beginning of the next turn's upkeep.

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

Arvinox, the Mind Flail isn't a creature unless you control three or more permanents you don't own.

At the beginning of your end step, exile the bottom card of each opponent's library face down. For as long as those cards remain exiled, you may look at them, you may cast permanent spells from among them, and you may spend mana as though it were mana of any color to cast those spells.

Changeling (This card is every creature type.)

As Bloodline Pretender enters the battlefield, choose a creature type.

Whenever another creature of the chosen type enters the battlefield under your control, put a +1/+1 counter on Bloodline Pretender.

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.

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

{2}, {T}: Add {B} for each Swamp you control.

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.

Castle Vantress enters the battlefield tapped unless you control an Island.

{T}: Add {U}.

{2}{U}{U}, {T}: Scry 2.

As Cavern of Souls enters the battlefield, choose a creature type.

{T}: Add {C}.

{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

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}.

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.

Undaunted (This spell costs {1} less to cast for each opponent.)

Destroy two target creatures.

Return target nonland permanent you don't control to its owner's hand.

Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

If you control a commander, you may cast this spell without paying its mana cost.

Exile target creature.

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.

Search your library for a card, put that card into your hand, then shuffle.

Dimir Aqueduct enters the battlefield tapped.

When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand.

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

Choose one --

• Counter target sorcery spell.

• Destroy target creature with power 2 or less.

• Look at the top three cards of target player's library. Put one back and the rest into that player's graveyard.

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

Reach

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)

As long as Doom Weaver is paired with another creature, each of those creatures has "When this creature dies, draw cards equal to its power."

As Door of Destinies enters the battlefield, choose a creature type.

Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.

Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.

Choose one. If you control a commander as you cast this spell, you may choose both.

• Target player draws X cards.

• Target player mills twice X cards.

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.

Drowned Catacomb enters the battlefield tapped unless you control an Island or a Swamp.

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

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.

Enchant creature you control

At the beginning of your upkeep, create a token that's a copy of enchanted creature, except the token is 1/1.

When enchanted creature dies, if that creature was a Horror, return Endless Evil to its owner's hand.

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

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

Fetid Pools enters the battlefield tapped.

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

If you control a commander, you may cast this spell without paying its mana cost.

Counter target noncreature spell.

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 Gollum, Patient Plotter leaves the battlefield, the Ring tempts you.

{B}, Sacrifice a creature: Return Gollum from your graveyard to your hand. Activate only as a sorcery.

Whenever Gollum, Scheming Guide attacks, look at the top two cards of your library, put them back in any order, then choose land or nonland. An opponent guesses whether the top card of your library is the chosen kind. Reveal that card. If they guessed right, remove Gollum from combat. Otherwise, you draw a card and Gollum can't be blocked this turn.

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.

As Herald's Horn enters the battlefield, choose a creature type.

Creature spells you cast of the chosen type cost {1} less to cast.

At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

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.

As Icon of Ancestry enters the battlefield, choose a creature type.

Creatures you control of the chosen type get +1/+1.

{3}, {T}: Look at the top three cards of your library. You may reveal a creature card of the chosen type from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

This spell costs {3} less to cast if an opponent has seven or more cards in their graveyard.

Draw four cards.

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({B/P} can be paid with either {B} or 2 life.)

Lifelink

For each {B} in a cost, you may pay 2 life rather than pay that mana.

Whenever you cast a black spell, put a +1/+1 counter on K'rrik, Son of Yawgmoth.

As Kindred Discovery enters the battlefield, choose a creature type.

Whenever a creature you control of the chosen type enters the battlefield or attacks, draw a card.

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)

Equip {0}

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

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.)

({T}: Add {U}.)

Mystic Sanctuary enters the battlefield tapped unless you control three or more other Islands.

When Mystic Sanctuary enters the battlefield untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Whenever Nemesis of Reason attacks, defending player mills ten 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.

When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Flying

When Psychic Symbiont enters the battlefield, target opponent discards a card and you draw a card.

When Ravenous Chupacabra enters the battlefield, destroy target creature an opponent controls.

As Reflections of Littjara enters the battlefield, choose a creature type.

Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

The Ring tempts you. Search your library for a card that shares a color with a legendary creature you control, reveal it, put it into your hand, then shuffle.

Menace

Whenever Sauron, the Necromancer attacks, exile target creature card from your graveyard. Create a tapped and attacking token that's a copy of that card, except it's a 3/3 black Wraith with menace. At the beginning of the next end step, exile that token unless Sauron is your Ring-bearer.

As Secluded Courtyard enters the battlefield, choose a creature type.

{T}: Add {C}.

{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

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.

{3}{B}{B}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

As long as Sinuous Vermin is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

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}.

({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}.)

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)

Equip {1}

At the beginning of each end step, put a slime counter on each creature you don't control.

Creatures you don't control get -1/-1 for each slime counter on them.

Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.

{U}{B}, Sacrifice a Slug: Draw a card.

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.

Umbris, Fear Manifest gets +1/+1 for each card your opponents own in exile.

Whenever Umbris or another Nightmare or Horror enters the battlefield under your control, target opponent exiles cards from the top of their library until they exile a land card.

As Unclaimed Territory enters the battlefield, choose a creature type.

{T}: Add {C}.

{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

{T}: Add {C}.

{T}: Add {U} or {B}. Underground River deals 1 damage to you.

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

Each player mills three cards. Then you return up to two creature cards from your graveyard to your hand. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Each land is a Swamp in addition to its other land types.

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

As Vanquisher's Banner enters the battlefield, choose a creature type.

Creatures you control of the chosen type get +1/+1.

Whenever you cast a creature spell of the chosen type, draw a card.

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

As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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.

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

({T}: Add {B}.)

Witch's Cottage enters the battlefield tapped unless you control three or more other Swamps.

When Witch's Cottage enters the battlefield untapped, you may put target creature card from your graveyard on top of your library.

When Woe Strider enters the battlefield, create a 0/1 white Goat creature token.

Sacrifice another creature: Scry 1.

Escape--{3}{B}{B}, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Woe Strider escapes with two +1/+1 counters on it.

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.)