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.

Enchant creature card in a graveyard

When Animate Dead enters the battlefield, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.

Enchanted creature gets -1/-0.

{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.

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

{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Bojuka Bog enters the battlefield tapped.

When Bojuka Bog enters the battlefield, exile target player's graveyard.

{T}: Add {B}.

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.

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

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 the battlefield tapped.

{T}: Add {B}.

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 {U}.

{T}: Add {B}.

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

Flying

Whenever an opponent draws a card, you may draw two cards.

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.

Creeping Tar Pit enters the battlefield tapped.

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

{1}{U}{B}: Creeping Tar Pit becomes a 3/2 blue and black Elemental creature until end of turn and can't be blocked this turn. It's still a land.

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

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)

Target player mills half their library, rounded down.

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.")

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.

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

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

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.

{T}: Add one mana of any color that a land an opponent controls could produce.

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

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

{T}: Add one mana of any color that a land an opponent controls could produce.

Each opponent mills fourteen cards.

Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

When you cycle Fractured Sanity, each opponent mills four cards.

Put target creature card from a graveyard onto the battlefield under your control with a corpse counter on it. If that creature would leave the battlefield, exile it instead of putting it anywhere else.

You take the initiative.

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

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.

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.)

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.

Trample

When Hunted Horror enters the battlefield, target opponent creates two 3/3 green Centaur creature tokens with protection from black.

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

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.

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

Equip {0}

Kicker {3}{U}

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

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.

{T}: Add {C}.

{1}, {T}, Sacrifice Mind Stone: Draw a card.

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

Morphic Pool enters the battlefield tapped unless you have two or more opponents.

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

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

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.

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

Suspend 7--{1}{B} (Rather than cast this card from your hand, you may pay {1}{B} and exile it with seven time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, cast it without paying its mana cost. It has haste.)

Whenever a card is put into an opponent's graveyard from anywhere, if Nihilith is suspended, you may remove a time counter from Nihilith.

{T}: Add {U}.

Channel -- {3}{U}, Discard Otawara, Soaring City: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Path of Ancestry enters the battlefield tapped.

{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Indestructible

As long as your devotion to blue and black is less than seven, Phenax isn't a creature.

Creatures you control have "{T}: Target player mills X cards, where X is this creature's toughness."

As Phyrexian Revoker enters the battlefield, choose a nonland card name.

Activated abilities of sources with the chosen name can't be activated.

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

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

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

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

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.)

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

{T}: Add {U}. If you played a land this turn, add {B} instead.

{T}: Add {C}.

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

Landfall -- Whenever a land enters the battlefield under your control, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

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.

Shipwreck Marsh enters the battlefield tapped unless you control two or more other lands.

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

Devoid (This card has no color.)

Whenever a land enters the battlefield under an opponent's control, that player exiles the top two cards of their library and you draw two cards.

Sky Diamond enters the battlefield tapped.

{T}: Add {U}.

{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 {C}.

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

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.

{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

{T}: Add {C}.

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

{T}: Add {B}.

Channel -- {3}{B}, Discard Takenuma, Abandoned Mire: Mill three cards, then return a creature or planeswalker card from your graveyard to your hand. This ability costs {1} less to activate for each legendary creature you control.

{T}: Add {C}.

{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.

You have no maximum hand size.

{T}: Add {C}.

As an additional cost to cast this spell, pay X life.

All creatures get -X/-X until end of turn.

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.

{T}: Add {C}.

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

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

({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.

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

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

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.)