Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Zodiark, Umbral God

Indestructible
When Zodiark enters, each player sacrifices half the non-God creatures they control of their choice, rounded down.
Whenever a player sacrifices another creature, put a +1/+1 counter on Zodiark.

Ulamog, the Defiler

When you cast this spell, target opponent exiles the top half of their library, rounded up.
Ward—Sacrifice two permanents.
Ulamog enters with a number of +1/+1 counters on it equal to the greatest mana value among cards in exile.
Ulamog has annihilator X, where X is the number of +1/+1 counters on it.

Angel of Suffering

Flying
If damage would be dealt to you, prevent that damage and mill twice that many cards.

Out of the Tombs

At the beginning of your upkeep, put two eon counters on this enchantment, then mill cards equal to the number of eon counters on it.
If you would draw a card while your library has no cards in it, instead return a creature card from your graveyard to the battlefield. If you can't, you lose the game.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Szarekh, the Silent King

Flying
My Will Be Done — Whenever Szarekh attacks, mill three cards. You may put an artifact creature card or Vehicle card from among the cards milled this way into your hand.

Urborg, Tomb of Yawgmoth

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

Swamp

Stinkweed Imp

Flying
Whenever this creature deals combat damage to a creature, destroy that creature.
Dredge 5 (If you would draw a card, you may mill five cards instead. If you do, return this card from your graveyard to your hand.)

Oriq Loremage

{T}: Search your library for a card, put it into your graveyard, then shuffle. If it's an instant or sorcery card, put a +1/+1 counter on this creature.

Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Crow of Dark Tidings

Flying
When this creature enters or dies, mill two cards. (Put the top two cards of your library into your graveyard.)

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Sol Ring

Super State

Enchant creature you control
Enchanted creature has base power and toughness 9/9 and has flying, first strike, trample, and haste.
Whenever enchanted creature deals combat damage to an opponent, it deals that much damage to each other opponent.

Mikaeus, the Unhallowed

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a Human deals damage to you, destroy it.
Other non-Human creatures you control get +1/+1 and have undying. (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.)

Invoke Despair

Target opponent sacrifices a creature of their choice. If they can't, they lose 2 life and you draw a card. Then repeat this process for an enchantment and a planeswalker.

Bazaar of Baghdad

{T}: Draw two cards, then discard three cards.

Cabal Coffers

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

Siegfried, Famed Swordsman

Menace
When Siegfried enters, mill three cards. Then put X +1/+1 counters on Siegfried, where X is twice the number of creature cards in your graveyard.

Doomsday Excruciator

Flying
When this creature enters, if it was cast, each player exiles all but the bottom six cards of their library face down.
At the beginning of your upkeep, draw a card.

Doom Whisperer

Flying, trample
Pay 2 life: 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.)

Venomous Hierophant

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)

Pact Weapon

As long as this Equipment is attached to a creature, you don't lose the game for having 0 or less life.
Whenever equipped creature attacks, draw a card and reveal it. The creature gets +X/+X until end of turn and you lose X life, where X is that card's mana value.
Equip—Discard a card.

The War in Heaven

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — You draw three cards and you lose 3 life.
II — Mill three cards.
III — Choose up to three target creature cards with total mana value 8 or less in your graveyard. Return each of them to the battlefield with a necrodermis counter on it. They're artifacts in addition to their other types.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Painter's Servant

As this creature enters, choose a color.
All cards that aren't on the battlefield, spells, and permanents are the chosen color in addition to their other colors.

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Breach the Multiverse

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.

Bladed Pinions

Equipped creature has flying and first strike.
Equip {2}

Ravenous Gigamole

When this creature enters, mill three cards. You may put a creature card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on this creature. (To mill a card, put the top card of your library into your graveyard.)

Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Lich

As this enchantment enters, you lose life equal to your life total.
You don't lose the game for having 0 or less life.
If you would gain life, draw that many cards instead.
Whenever you're dealt damage, sacrifice that many nontoken permanents. If you can't, you lose the game.
When this enchantment is put into a graveyard from the battlefield, you lose the game.

Wailing Ghoul

When this creature enters, mill two cards. (Put the top two cards of your library into your graveyard.)

Silver Shroud Costume

Flash
When this Equipment enters, attach it to target creature you control. That creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
Equipped creature can't be blocked.
Equip {3}

Repay in Kind

Each player's life total becomes the lowest life total among all players.

Baron Helmut Zemo

Whenever you cast a black spell from your hand, Baron Helmut Zemo connives.
Boast — Exile any number of black cards from your graveyard with fifteen or more black mana symbols among their mana costs: Copy those exiled cards. You may cast up to three of the copies without paying their mana costs. (Activate only if this creature attacked this turn and only once each turn.)

Valgavoth's Faithful

{3}{B}, Sacrifice this creature: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Fleetfeather Sandals

Equipped creature has flying and haste.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Temporal Extortion

When you cast this spell, any player may pay half their life, rounded up. If a player does, counter Temporal Extortion.
Take an extra turn after this one.

Demonic Tutor

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

Necromancer's Assistant

When this creature enters, mill three cards.

Vile Entomber

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, search your library for a card, put that card into your graveyard, then shuffle.

Liliana, Death's Majesty

+1: Create a 2/2 black Zombie creature token. Mill two cards.
−3: Return target creature card from your graveyard to the battlefield. That creature is a black Zombie in addition to its other colors and types.
−7: Destroy all non-Zombie creatures.

Reaper from the Abyss

Flying
Morbid — At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.

Ulamog, the Ceaseless Hunger

When you cast this spell, exile two target permanents.
Indestructible
Whenever Ulamog attacks, defending player exiles the top twenty cards of their library.

Gravecrawler

This creature can't block.
You may cast this card from your graveyard as long as you control a Zombie.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Demonic Collusion

Buyback—Discard two cards. (You may discard two cards in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.)
Search your library for a card, put that card into your hand, then shuffle.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Diabolic Tutor

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Brotherhood Regalia

Equipped creature has ward {2}, is an Assassin in addition to its other types, and can't be blocked.
Equip legendary creature {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Sigil of Myrkul

At the beginning of combat on your turn, mill a card. When you do, if there are four or more creature cards in your graveyard, put a +1/+1 counter on target creature you control and it gains deathtouch until end of turn. (To mill a card, put the top card of your library into your graveyard.)

Forsaken Drifters

When this creature dies, mill four cards.

Arcane Signet

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

Valgavoth, Terror Eater

Flying, lifelink
Ward—Sacrifice three nonland permanents.
If a card you didn't control would be put into an opponent's graveyard from anywhere, exile it instead.
During your turn, you may play cards exiled with Valgavoth. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Demonic Embrace

Enchant creature
Enchanted creature gets +3/+1, has flying, and is a Demon in addition to its other types.
You may cast this card from your graveyard by paying 3 life and discarding a card in addition to paying its other costs.

Venomized Cat

Deathtouch
When this creature enters, mill two cards. (Put the top two cards of your library into your graveyard.)

Entreat the Dead

Return X target creature cards from your graveyard to the battlefield.
Miracle {X}{B}{B} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Dread Osseosaur

Menace
Whenever this creature enters or attacks, you may mill two cards. (You may put the top two cards of your library into your graveyard.)

Visage of Dread

When this artifact enters, target opponent reveals their hand. You choose an artifact or creature card from it. That player discards that card.
Craft with two creatures {5}{B} ({5}{B}, Exile this artifact, Exile the two from among creatures you control and/or creature cards in your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Visage of Dread // Dread Osseosaur

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Crypt of Agadeem

This land enters tapped.
{T}: Add {B}.
{2}, {T}: Add {B} for each black creature card in your graveyard.

Platinum Angel

Flying
You can't lose the game and your opponents can't win the game.

Vampiric Tutor

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