Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Arcane Signet

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

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Archmage of Runes

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, draw a card.

Shipwreck Marsh

This land enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Roaming Throne

Ward {2}
As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Command Tower

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Infernal Grasp

Destroy target creature. You lose 2 life.

Sol Ring

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Nazgûl

Deathtouch
When this creature enters, 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.

Frantic Search

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

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Soothing of Sméagol

Return target nontoken creature to its owner's hand. The Ring tempts you.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Swamp

Ringsight

The Ring tempts you. Search your library for a card that shares a color with a legendary creature you control, reveal it, put it into your hand, then shuffle.

Serum Visions

Night's Whisper

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Orcish Bowmasters

Flash
When this creature enters and whenever an opponent draws a card except the first one they draw in each of their draw steps, this creature deals 1 damage to any target. Then amass Orcs 1.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Counterspell

Minas Morgul, Dark Fortress

Minas Morgul enters tapped.
{T}: Add {B}.
{3}{B}, {T}: Put a shadow counter on target creature. For as long as that creature has a shadow counter on it, it's a Wraith in addition to its other types. (A creature with shadow can block or be blocked by only creatures with shadow.)

Changeling Outcast

Changeling (This card is every creature type.)
This creature can't block and can't be blocked.

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Morphic Pool

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Negate

Dark Ritual

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Island

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Kindred Discovery

As this enchantment enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Witch-king of Angmar

Flying
Whenever one or more creatures deal combat damage to you, each opponent sacrifices a creature of their choice that dealt combat damage to you this turn. The Ring tempts you.
Discard a card: Witch-king of Angmar gains indestructible until end of turn. Tap it.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Thought Vessel

Raise the Palisade

Choose a creature type. Return all creatures that aren't of the chosen type to their owners' hands.

Sauron, the Necromancer

Menace
Whenever Sauron 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.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Ringwraiths

When this creature enters, 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 this card from your graveyard to your hand.

Tainted Isle

{T}: Add {C}.
{T}: Add {U} or {B}. Activate only if you control a Swamp.

Witch-king, Bringer of Ruin

Flying
Whenever Witch-king attacks, defending player sacrifices a creature with the least power among creatures they control.

Spark Double

You may have this creature 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.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Birthday Escape

Polluted Delta

{T}, Pay 1 life, Sacrifice this land: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Call of the Ring

At the beginning of your upkeep, the Ring tempts you.
Whenever you choose a creature as your Ring-bearer, you may pay 2 life. If you do, draw a card.

Glorious Gale

Counter target creature spell. If it was a legendary spell, the Ring tempts you.

Go for the Throat

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Black Market Connections

At the beginning of your first main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It is every creature type.)

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Lord of the Nazgûl

Flying
Wraiths you control have protection from Ring-bearers.
Whenever you cast an instant or sorcery spell, create a 3/3 black Wraith creature token with menace. Then if you control nine or more Wraiths, Wraiths you control have base power and toughness 9/9 until end of turn.

Path of Ancestry

This land enters 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.)

Darkwater Catacombs

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Sam's Desperate Rescue

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

Claim the Precious

Destroy target creature. The Ring tempts you.

Temple of Cyclical Time

(Transforms from Ojer Pakpatiq, Deepest Epoch.)
{T}: Add {U}. Remove a time counter from this land.
{2}{U}, {T}: Transform this land. Activate only if it has no time counters on it and only as a sorcery.

Ojer Pakpatiq, Deepest Epoch

Flying
Whenever you cast an instant spell from your hand, it gains rebound. (Exile it as it resolves. At the beginning of your next upkeep, you may cast it from exile without paying its mana cost.)
When Ojer Pakpatiq dies, return it to the battlefield tapped and transformed under its owner's control with three time counters on it.

Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time

Dimir Signet

Gríma, Saruman's Footman

Gríma can't be blocked.
Whenever Gríma deals combat damage to a player, that player exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then that player puts the exiled cards that weren't cast this way on the bottom of their library in a random order.

Feed the Swarm

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

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Canoptek Wraith

Wraith Form — This creature can't be blocked.
Transdimensional Scout — When this creature deals combat damage to a player, you may pay {3} and sacrifice it. If you do, choose a land you control. Then search your library for up to two basic land cards which have the same name as the chosen land, put them onto the battlefield tapped, then shuffle.

Sauron's Ransom

Choose an opponent. They look at the top four cards of your library and separate them into a face-down pile and a face-up pile. Put one pile into your hand and the other into your graveyard. The Ring tempts you.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Choked Estuary

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped.
{T}: Add {U} or {B}.

Gandalf, Friend of the Shire

Flash
You may cast sorcery spells as though they had flash.
Whenever the Ring tempts you, if you chose a creature other than Gandalf as your Ring-bearer, draw a card.