One Ring to Rule Them All

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — The Ring tempts you, then each player mills cards equal to your Ring-bearer's power.
II — Destroy all nonlegendary creatures.
III — Each opponent loses 1 life for each creature card in that player's graveyard.

Sewer Nemesis

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.

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

King Macar, the Gold-Cursed

Inspired — Whenever King Macar becomes untapped, you may exile target creature. If you do, create a Gold token. (It's an artifact with "Sacrifice this token: Add one mana of any color.")

Crucible of Worlds

Captain N'ghathrod

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.

Black Oak of Odunos

Defender
{B}, Tap another untapped creature you control: This creature gets +1/+1 until end of turn.

Blight Pile

Defender
{2}{B}, {T}: Each opponent loses X life, where X is the number of creatures with defender you control.

Barrier of Bones

Defender
When this creature enters, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Psychic Strike

Counter target spell. Its controller mills two cards.

Marvo, Deep Operative

Whenever Marvo attacks, clash with defending player. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)
Whenever you win a clash, draw a card. Then you may cast a spell from your hand with mana value 8 or less without paying its mana cost.

Abyssal Persecutor

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

Revealing Eye

Menace
When this creature transforms into Revealing Eye, target opponent reveals their hand. You may choose a nonland card from it. If you do, that player discards that card, then draws a card.

Concealing Curtains

Defender
{2}{B}: Transform this creature. Activate only as a sorcery.

Concealing Curtains // Revealing Eye

Wall of Kelp

Defender (This creature can't attack.)
{U}{U}, {T}: Create a 0/1 blue Plant Wall creature token with defender named Kelp.

Spoils of Evil

For each artifact or creature card in target opponent's graveyard, add {C} and you gain 1 life.

Awoken Horror

When this creature transforms into Awoken Horror, return all non-Horror creatures to their owners' hands.

Thing in the Ice

Defender
This creature enters with four ice counters on it.
Whenever you cast an instant or sorcery spell, remove an ice counter from this creature. Then if it has no ice counters on it, transform it.

Thing in the Ice // Awoken Horror

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Clinging Anemones

Defender
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Basalt Golem

This creature can't be blocked by artifact creatures.
Whenever this creature becomes blocked by a creature, that creature's controller sacrifices it at end of combat. If the player does, they create a 0/2 colorless Wall artifact creature token with defender.

Unhallowed Phalanx

Excavated Wall

Defender
{1}, {T}: Mill a card. (Put the top card of your library into your graveyard.)

Coral Colony

Defender
{1}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender. (To mill a card, a player puts the top card of their library into their graveyard.)

Aegis Turtle

Unseal the Necropolis

Each player mills three cards. Then you return up to two creature cards from your graveyard to your hand. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

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.)

Consulate Skygate

Defender
Reach (This creature can block creatures with flying.)

Wall of Mist

Dreamscape Artist

{2}{U}, {T}, Discard a card, Sacrifice a land: Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Kaijin of the Vanishing Touch

Defender (This creature can't attack.)
Whenever this creature blocks a creature, return that creature to its owner's hand at end of combat. (Return it only if it's on the battlefield.)

Doorkeeper

Defender
{2}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender.

Armillary Sphere

{2}, {T}, Sacrifice this artifact: Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.

Revenant

Flying
Revenant's power and toughness are each equal to the number of creature cards in your graveyard.

Amaranthine Wall

Defender
{2}: This creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Umbra Stalker

Chroma — Umbra Stalker's power and toughness are each equal to the number of black mana symbols in the mana costs of cards in your graveyard.

Coral Barrier

Defender (This creature can't attack.)
When this creature enters, create a 1/1 blue Squid creature token with islandwalk. (It can't be blocked as long as defending player controls an Island.)

Dark Ritual

Nighthawk Scavenger

Flying, deathtouch, lifelink
Nighthawk Scavenger's power is equal to 1 plus the number of card types among cards in your opponents' graveyards.

Gleaming Barrier

Defender
When this creature dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Souls of the Lost

As an additional cost to cast this spell, discard a card or sacrifice a permanent.
Fathomless descent — Souls of the Lost's power is equal to the number of permanent cards in your graveyard and its toughness is equal to that number plus 1.

Cemetery Gate

Defender (This creature can't attack.)
Protection from black

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.

Roiling Horror

Roiling Horror's power and toughness are each equal to your life total minus the life total of an opponent with the most life.
Suspend X—{X}{B}{B}{B}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{B}{B}{B} and exile it with X time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)
Whenever a time counter is removed from this card while it's exiled, target player loses 1 life and you gain 1 life.

Scourge of the Skyclaves

Kicker {4}{B}
When you cast this spell, if it was kicked, each player loses half their life, rounded up.
Scourge of the Skyclaves's power and toughness are each equal to 20 minus the highest life total among players.

Carrion Wall

Defender (This creature can't attack.)
{1}{B}: Regenerate this creature.

Dramatic Reversal

Untap all nonland permanents you control.

Shadow Kin

Flash
At the beginning of your upkeep, each player mills three cards. You may exile a creature card from among the cards milled this way. If you do, this creature becomes a copy of that card, except it has this ability.

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Glacial Wall

Chimney Goyf

Flying
Chimney Goyf's power is equal to the number of card types among cards in all graveyards and its toughness is equal to that number plus 1.
When Chimney Goyf dies, target opponent puts a card from their hand on top of their library.

Deep Freeze

Enchant creature
Enchanted creature has base power and toughness 0/4, has defender, loses all other abilities, and is a blue Wall in addition to its other colors and types.

Custodian of the Trove

Necrogoyf

Necrogoyf's power is equal to the number of creature cards in all graveyards.
At the beginning of each player's upkeep, that player discards a card.
Madness {1}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Bonded Fetch

Defender, haste
{T}: Draw a card, then discard a card.

Academy Wall

Defender
Whenever you cast an instant or sorcery spell, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Wall of Junk

Defender (This creature can't attack.)
When this creature blocks, return it to its owner's hand at end of combat. (Return it only if it's on the battlefield.)

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.