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 two cards. Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Draw two cards, then discard two cards. Untap up to three lands.

+2: Each player draws a card. −1: Target player draws a card. −10: Target player mills twenty cards.

Equipped creature gets +1/-1. Whenever equipped creature dies, draw two cards. Equip {1}

Target player mills two cards. Draw a card.

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.) Draw three cards.

Other blue creatures you control have "Whenever this creature becomes tapped, draw a card, then discard a card." Other artifact creatures you control get +1/+1. {U/P}: Until end of turn, target creature you control becomes a blue artifact in addition to its other colors and types. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

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.

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.

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

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.

As an additional cost to cast this spell, sacrifice a creature. Return a creature card from your graveyard to the battlefield, then return another creature card from your graveyard to your hand.

Return target creature card from your graveyard to the battlefield. Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it.) Mill five cards, then return a creature card from your graveyard to the battlefield.

Return target nonlegendary creature card from your graveyard to the battlefield with a -1/-1 counter on it.

Tempting offer — Return a creature card from your graveyard to the battlefield. Each opponent may return a creature card from their graveyard to the battlefield. For each opponent who does, return a creature card from your graveyard to the battlefield.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. Cycling {2} ({2}, Discard this card: Draw a card.)

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

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

({T}: Add {U}.)

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

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.)

({T}: Add {U} or {B}.) Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

When Court of Cunning enters the battlefield, 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.)

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.

At the beginning of each player's upkeep, that player mills X cards, where X is the number of cards in their hand.

Whenever you cast a blue spell, target player mills two cards.

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.

{T}: Each player mills a card.

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.

Whenever you draw a card, each opponent mills two 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.

When Teferi's Tutelage enters the battlefield, 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.)

{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 Commander's Sphere: Draw a card.

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

{T}: Add {U}. {2}{U}: Put an hour counter on Midnight Clock. At the beginning of each upkeep, put an hour counter on Midnight Clock. When the twelfth hour counter is put on Midnight Clock, shuffle your hand and graveyard into your library, then draw seven cards. Exile Midnight Clock.

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

{T}, Exile Surveyor's Scope: Search your library for up to X basic land cards, where X is the number of players who control at least two more lands than you. Put those cards onto the battlefield, then shuffle.

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

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

Counter target spell. Its controller mills three 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.

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

When Fraying Line enters the battlefield, put a rope counter on target creature you control. At the beginning of each player's upkeep, that player may pay {2}. If they do, they put a rope counter on a creature they control. Otherwise, exile Fraying Line and each creature without a rope counter on it, then remove all rope counters from all creatures.

Destroy target nonartifact creature.

Counter target spell unless its controller pays {3}.

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.

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.

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

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.

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.)

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.) Create a token that's a copy of target permanent you 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.

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.

Kicker {3}{U} Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Whenever a permanent becomes untapped, that permanent's controller mills a card.

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.