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.

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

The Cruelty of Gix

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — Target opponent reveals their hand. You choose a creature or planeswalker card from it. That player discards that card.
II — Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.
III — Put target creature card from a graveyard onto the battlefield under your control.

Old Man Willow

Old Man Willow's power and toughness are each equal to the number of lands you control.
Whenever Old Man Willow attacks, you may sacrifice another creature or a token. When you do, target creature an opponent controls gets -2/-2 until end of turn.

Uruk-hai Berserker

When Uruk-hai Berserker enters the battlefield, the Ring tempts you.

Mithril Coat

Flash
Indestructible
When Mithril Coat enters the battlefield, attach it to target legendary creature you control.
Equipped creature has indestructible.
Equip {3}

Claim the Precious

Destroy target creature. The Ring tempts you.

Vampiric Rites

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Ringwraiths

When Ringwraiths enters the battlefield, target creature an opponent controls gets -3/-3 until end of turn. If that creature is legendary, its controller loses 3 life.
When the Ring tempts you, return Ringwraiths from your graveyard to your hand.

Haunted Mire

({T}: Add {B} or {G}.)
Haunted Mire enters the battlefield tapped.

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Shortcut to Mushrooms

When Shortcut to Mushrooms enters the battlefield, the Ring tempts you.
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, put a +1/+1 counter on target creature you control.

Lash of the Balrog

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

Great Hall of the Citadel

{T}: Add {C}.
{1}, {T}: Add two mana in any combination of colors. Spend this mana only to cast legendary spells.

Nazgûl

Deathtouch
When Nazgûl enters the battlefield, the Ring tempts you.
Whenever the Ring tempts you, put a +1/+1 counter on each Wraith you control.
A deck can have up to nine cards named Nazgûl.

Primeval Bounty

Whenever you cast a creature spell, create a 3/3 green Beast creature token.
Whenever you cast a noncreature spell, put three +1/+1 counters on target creature you control.
Landfall — Whenever a land enters the battlefield under your control, you gain 3 life.

Arasta of the Endless Web

Reach
Whenever an opponent casts an instant or sorcery spell, create a 1/2 green Spider creature token with reach.

Arcane Signet

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

Sméagol, Helpful Guide

At the beginning of your end step, if a creature died under your control this turn, the Ring tempts you.
Whenever the Ring tempts you, target opponent reveals cards from the top of their library until they reveal a land card. Put that card onto the battlefield tapped under your control and the rest into their graveyard.

Lobelia Sackville-Baggins

Flash
Menace
When Lobelia Sackville-Baggins enters the battlefield, exile target creature card from an opponent's graveyard that was put there from the battlefield this turn, then create X Treasure tokens, where X is the exiled card's power.

Ezuri's Predation

For each creature your opponents control, create a 4/4 green Phyrexian Beast creature token. Each of those tokens fights a different one of those creatures.

Command Tower

Gollum's Bite

Target creature gets -2/-2 until end of turn.
{3}{B}, Exile Gollum's Bite from your graveyard: The Ring tempts you. Activate only as a sorcery.

Inherited Envelope

When Inherited Envelope enters the battlefield, the Ring tempts you.
{T}: Add one mana of any color.

Sam's Desperate Rescue

Return target creature card from your graveyard to your hand. The Ring tempts you.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Sol Ring

Bombadil's Song

Target creature you control gets +1/+1 and gains hexproof until end of turn. The Ring tempts you. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Summon Undead

You may mill three cards. Then return a creature card from your graveyard to the battlefield. (To mill a card, put the top card of your library into your graveyard.)

Ravenous Baloth

Black Dragon Gate

Black Dragon Gate enters the battlefield tapped.
As Black Dragon Gate enters the battlefield, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Gríma Wormtongue

Your opponents can't gain life.
{T}, Sacrifice another creature: Target player loses 1 life. If the sacrificed creature was legendary, amass Orcs 2.

The Shire

The Shire enters the battlefield tapped unless you control a legendary creature.
{T}: Add {G}.
{1}{G}, {T}, Tap an untapped creature you control: Create a Food token.

Sauron, the Necromancer

Menace
Whenever Sauron, the Necromancer attacks, exile target creature card from your graveyard. Create a tapped and attacking token that's a copy of that card, except it's a 3/3 black Wraith with menace. At the beginning of the next end step, exile that token unless Sauron is your Ring-bearer.

Feign Death

Until end of turn, target creature gains "When this creature dies, return it to the battlefield tapped under its owner's control with a +1/+1 counter on it."

Riveteers Overlook

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

Forest

Zendikar's Roil

Landfall — Whenever a land enters the battlefield under your control, create a 2/2 green Elemental creature token.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Braids's Frightful Return

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — You may sacrifice a creature. If you do, each opponent discards a card.
II — Return target creature card from your graveyard to your hand.
III — Target opponent may sacrifice a nonland, nontoken permanent. If they don't, they lose 2 life and you draw a card.

Enraged Huorn

Trample
When Enraged Huorn enters the battlefield, the Ring tempts you.

Undercity Scrounger

{T}: Create a Treasure token. Activate only if a creature died this turn. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Panharmonicon

If an artifact or creature entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Mirrormere Guardian

When Mirrormere Guardian dies, the Ring tempts you.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

The Black Breath

Creatures your opponents control get -1/-1 until end of turn. The Ring tempts you.

Dúnedain Rangers

Landfall — Whenever a land enters the battlefield under your control, if you don't control a Ring-bearer, the Ring tempts you.

Rampaging Baloths

Trample
Landfall — Whenever a land enters the battlefield under your control, you may create a 4/4 green Beast creature token.

The Grey Havens

When The Grey Havens enters the battlefield, scry 1.
{T}: Add {C}.
{T}: Add one mana of any color among legendary creature cards in your graveyard.

Rise of the Witch-king

Each player sacrifices a creature. If you sacrificed a creature this way, you may return another permanent card from your graveyard to the battlefield.

Nemata, Primeval Warden

Reach
If a creature an opponent controls would die, exile it instead. When you do, create a 1/1 green Saproling creature token.
{G}, Sacrifice a Saproling: Nemata, Primeval Warden gets +2/+2 until end of turn.
{1}{B}, Sacrifice two Saprolings: Draw a card.

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Blanchwood Armor

Enchant creature
Enchanted creature gets +1/+1 for each Forest you control.

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Braids, Arisen Nightmare

At the beginning of your end step, you may sacrifice an artifact, creature, enchantment, land, or planeswalker. If you do, each opponent may sacrifice a permanent that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.