Glimpse the Unthinkable

Colossification

Enchant creature
When Colossification enters, tap enchanted creature.
Enchanted creature gets +20/+20.

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Old Stickfingers

When you cast this spell, reveal cards from the top of your library until you reveal X creature cards. Put all creature cards revealed this way into your graveyard, then put the rest on the bottom of your library in a random order.
Old Stickfingers's power and toughness are each equal to the number of creature cards in your graveyard.

Sol Ring

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.

Argothian Enchantress

Shroud (This creature can't be the target of spells or abilities.)
Whenever you cast an enchantment spell, draw a card.

Double Major

Copy target creature spell you control, except it isn't legendary if the spell is legendary. (A copy of a creature spell becomes a token.)

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

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.)

Demogorgon's Clutches

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.)

Wretched Bonemass

Wretched Bonemass's power and toughness are each equal to the total power of the exiled cards used to craft it.
Wretched Bonemass has flying as long as an exiled card used to craft it has flying. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection, reach, trample, and vigilance.

Altar of the Wretched

When Altar of the Wretched enters, you may sacrifice a nontoken creature. If you do, draw X cards, then mill X cards, where X is that creature's power.
Craft with one or more creatures {2}{B}{B}
{2}{B}: Return Altar of the Wretched from your graveyard to your hand.

Altar of the Wretched // Wretched Bonemass

Disturbing Conversion

Flash
Enchant creature
When Disturbing Conversion enters, each player mills two cards.
Enchanted creature gets -X/-0, where X is the number of cards in its controller's graveyard.

Diligent Excavator

Whenever you cast a historic spell, target player mills two cards. (Artifacts, legendaries, and Sagas are historic.)

You Find the Villains' Lair

Choose one —
• Foil Their Scheme — Counter target spell.
• Learn Their Secrets — Draw two cards, then discard two cards.

Crawling Infestation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more creature cards are put into your graveyard from anywhere during your turn, create a 1/1 green Insect creature token. This ability triggers only once each turn.

Bond of Insight

Each player mills four cards. Return up to two instant and/or sorcery cards from your graveyard to your hand. Exile Bond of Insight.

Blanchwood Prowler

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

Arcane Signet

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

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters, 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.

Thirst for Knowledge

Draw three cards. Then discard two cards unless you discard an artifact card.

Boneyard Mycodrax

Boneyard Mycodrax's power and toughness are each equal to the number of other creature cards in your graveyard.
Scavenge {4}{B} ({4}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Corpse Churn

Mill three cards, then you may return a creature card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Muldrotha, the Gravetide

During each of your turns, you may play a land and cast a permanent spell of each permanent type from your graveyard. (If a card has multiple permanent types, choose one as you play it.)

Akawalli, the Seething Tower

Descend 4 — As long as there are four or more permanent cards in your graveyard, Akawalli, the Seething Tower gets +2/+2 and has trample.
Descend 8 — As long as there are eight or more permanent cards in your graveyard, Akawalli gets an additional +2/+2 and can't be blocked by more than one creature.

Cemetery Tampering

Hideaway 5 (When this enchantment enters, look at the top five cards of your library, exile one face down, then put the rest on the bottom in a random order.)
At the beginning of your upkeep, you may mill three cards. Then if there are twenty or more cards in your graveyard, you may play the exiled card without paying its mana cost.

Aven Heartstabber

Flying
As long as there are five or more mana values among cards in your graveyard, Aven Heartstabber gets +2/+2 and has deathtouch.
When Aven Heartstabber dies, mill two cards, then draw a card.

Didn't Say Please

Counter target spell. Its controller mills three cards.

Can't Wake Up

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Cruel Somnophage

Cruel Somnophage's power and toughness are each equal to the number of creature cards in all graveyards.

Cruel Somnophage // Can't Wake Up

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Teferi's Tutelage

When Teferi's Tutelage 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.)

Dimir Signet

Bow of Nylea

Attacking creatures you control have deathtouch.
{1}{G}, {T}: Choose one —
• Put a +1/+1 counter on target creature.
• Bow of Nylea deals 2 damage to target creature with flying.
• You gain 3 life.
• Put up to four target cards from your graveyard on the bottom of your library in any order.

Cauldron's Gift

Adamant — If at least three black mana was spent to cast this spell, mill four cards.
You may choose a creature card in your graveyard. If you do, return it to the battlefield with an additional +1/+1 counter on it.

Crawling Sensation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more land cards are put into your graveyard from anywhere for the first time each turn, create a 1/1 green Insect creature token.

Carrion Grub

Carrion Grub gets +X/+0, where X is the greatest power among creature cards in your graveyard.
When Carrion Grub enters, mill four cards. (Put the top four cards of your library into your graveyard.)

Devourer of Memory

Whenever one or more cards are put into your graveyard from your library, Devourer of Memory gets +1/+1 until end of turn and can't be blocked this turn.
{1}{U}{B}: Mill a card.

Enchantress's Presence

Whenever you cast an enchantment spell, draw a card.

Bygone Marvels

Descend 8 — When you cast this spell, if there are eight or more permanent cards in your graveyard, copy this spell twice. You may choose new targets for the copies.
Return target permanent card from your graveyard to your hand. Exile Bygone Marvels.

Verduran Enchantress

Whenever you cast an enchantment spell, you may draw a card.

The Ancient One

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.

Golgari Signet

Dig Up the Body

Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell.)
Mill two cards, then you may return a creature card from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Another Chance

You may mill two cards. Then return up to two creature cards from your graveyard to your hand. (To mill two cards, put the top two cards of your library into your graveyard.)

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

The Myriad Pools

(Transforms from The Everflowing Well.)
{T}: Add {U}.
Whenever you cast a permanent spell using mana produced by The Myriad Pools, up to one other target permanent you control becomes a copy of that spell until end of turn.

The Everflowing Well

When The Everflowing Well enters, mill two cards, then draw two cards.
Descend 8 — At the beginning of your upkeep, if there are eight or more permanent cards in your graveyard, transform The Everflowing Well.

The Everflowing Well // The Myriad Pools

Chill of Foreboding

Each player mills five cards.
Flashback {7}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Ancient of the Equinox

Autumnal Gloom

{B}: Mill a card.
Delirium — At the beginning of your end step, if there are four or more card types among cards in your graveyard, transform Autumnal Gloom.

Autumnal Gloom // Ancient of the Equinox

Artisan of Kozilek

When you cast this spell, you may return target creature card from your graveyard to the battlefield.
Annihilator 2 (Whenever this creature attacks, defending player sacrifices two permanents of their choice.)

Deranged Assistant

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