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.)

Target player draws X cards and loses X life, where X is the number of cards in their graveyard.

This land enters tapped. As this land enters, choose a color other than black. {T}: Add {B} or one mana of the chosen color.

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped. {T}: Add {U} or {B}.

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

This land enters tapped. {T}: Add {U} or {B}. {1}{U}{B}: This land 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.

This land enters tapped. When this land enters, return a land you control to its owner's hand. {T}: Add {U}{B}.

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

This land enters tapped. When this land enters, return a land you control to its owner's hand. {T}: Add {C}{C}.

({T}: Add {U}.)

When this land enters, sacrifice it. When you do, search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

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

When this land enters, sacrifice it. When you do, search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

This land enters tapped. {T}: Add {U}. {3}{U}{B}{B}, {T}, Sacrifice this land: Mill four cards, then return a creature card from your graveyard to the battlefield tapped. (To mill a card, put the top card of your library into your graveyard.)

This land enters tapped. {T}: Add {U} or {B}. {2}{U}{B}: Until end of turn, this land becomes a 4/4 blue and black Shark creature with deathtouch. It's still a land. Whenever this land attacks, target player mills four cards.

({T}: Add {B}.)

This land enters tapped. As it enters, choose a color other than blue. {T}: Add {U} or one mana of the chosen color.

This land enters tapped. As it enters, choose a color other than black. {T}: Add {B} or one mana of the chosen color.

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.

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

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.)

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.

Enchant player At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Replicate—Tap an untapped Horror you control. (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.) Exile target instant or sorcery card from a graveyard and copy it. You may cast the copy without paying its mana cost. Exile Psionic Ritual.

At the beginning of each end step, if an opponent lost 2 or more life this turn, you may put a quest counter on this enchantment. (Damage causes loss of life.) Whenever a card is put into an opponent's graveyard from anywhere, if this enchantment has three or more quest counters on it, you may have that player lose 2 life. If you do, you gain 2 life.

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

{T}: Add one mana of any color in your commander's color identity. Sacrifice this artifact: Draw a card.

You have no maximum hand size. {T}: Add one mana of any color.

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

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

{T}: Add {C}. {1}, {T}, Sacrifice this artifact: Draw a card.

If you would draw a card while you have no cards in hand, draw two cards instead. If you would gain life while you have 5 or less life, you gain twice that much life instead. {T}: Add one mana of any color.

When this enchantment enters, you become the monarch. At the beginning of your upkeep, any number of target players each mill two cards. If you're the monarch, each of those players mills ten cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Each opponent mills fourteen cards. Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.) When you cycle this card, each opponent mills four cards.

Whenever an opponent casts a spell, that player mills two cards.

Whenever a creature attacks you or a planeswalker you control, that creature's controller mills two cards.

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way. Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.) When you cycle this card, all creatures get -2/-2 until end of turn.

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

Put target creature card from a graveyard onto the battlefield under your control. It gains indestructible. If it's your turn, scry 2.

Flying Whenever this creature deals combat damage to a player, roll a d20. When you do, put any number of target creature cards with total mana value X or less from graveyards onto the battlefield under your control, where X is the result.

Flying Whenever this creature deals combat damage to a player, roll a d20. Draw cards equal to the result. You have no maximum hand size for the rest of the game.

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.

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.

When Gothmog enters, amass Orcs 1. (Put a +1/+1 counter on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.) Creature tokens you control have deathtouch.

Aberrant Tinkering — When this creature enters 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 this creature attacks and isn't blocked, defending player loses 1 life for each card in their graveyard.

Mortivore's power and toughness are each equal to the number of creature cards in all graveyards. {B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Whenever this creature attacks, defending player mills ten cards.

As this creature enters, 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.

Whenever this creature enters 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.

Descend 8 — The Ancient One can't attack or block unless there are eight or more permanent cards in your graveyard. {2}{U}{B}: Draw a card, then discard a card. When you discard a card this way, target player mills cards equal to its mana value.

If an opponent searched their library this turn, you may pay {0} rather than pay this spell's mana cost. Target opponent mills thirteen cards.

Enchant player At the beginning of enchanted player's upkeep, that player reveals cards from the top of their library until they reveal a creature card. Put that card onto the battlefield under your control. That player puts the rest of the revealed cards into their graveyard.

Target opponent discards two cards, mills two cards, and loses 2 life. (To mill a card, a player puts the top card of their library into their graveyard.)

Target player mills ten cards.

{2}, {T}: Target player mills two cards.

{2}, {T}: Target opponent mills three cards. Put a land card from their graveyard onto the battlefield tapped under your control. It gains "If this land would leave the battlefield, exile it instead of putting it anywhere else." {10}, {T}, Sacrifice Realmbreaker: Search your library for any number of Praetor cards, put them onto the battlefield, then shuffle.

This creature can't attack or block unless an opponent has eight or more cards in their graveyard. {2}, {T}: Target player mills two cards. (They put the top two cards of their library into their graveyard.)

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}

When this enchantment enters, draw a card, then discard a card. Whenever you draw a card, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)

Counter target spell. Its controller mills three cards.

Target player mills two cards. Draw a card.