Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Soul Shatter

Each opponent sacrifices a creature or planeswalker with the greatest mana value among creatures and planeswalkers they control.

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.)

Getting

Sublime Epiphany

Choose one or more —
• Counter target spell.
• Counter target activated or triggered ability.
• Return target nonland permanent to its owner's hand.
• Create a token that's a copy of target creature you control.
• Target player draws a card.

Dimir Signet

Pongify

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

Infernal Grasp

Destroy target creature. You lose 2 life.

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

Languish

All creatures get -4/-4 until end of turn.

Lotus Field

Hexproof
This land enters tapped.
When this land enters, sacrifice two lands.
{T}: Add three mana of any one color.

Wizards of Thay

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Instant and sorcery spells you cast cost {1} less to cast.
You may cast sorcery spells as though they had flash.

Metallic Mimic

As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters with an additional +1/+1 counter on it.

Primal Wellspring

(Transforms from Primal Amulet.)
{T}: Add one mana of any color. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Primal Amulet

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, put a charge counter on this artifact. Then if there are four or more charge counters on it, you may remove those counters and transform it.

Primal Amulet // Primal Wellspring

Reverse the Polarity

Choose one —
• Counter all other spells.
• Switch each creature's power and toughness until end of turn.
• Creatures can't be blocked this turn.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (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.)

Sunken Hollow

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

Jwari Ruins

Jwari Disruption

Counter target spell unless its controller pays {1}.

Jwari Disruption // Jwari Ruins

Troll of Khazad-dûm

This creature can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Bender's Waterskin

Untap this artifact during each other player's untap step.
{T}: Add one mana of any color.

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Professor Onyx

Magecraft — Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life.
+1: You lose 1 life. Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
−3: Each opponent sacrifices a creature with the greatest power among creatures that player controls.
−8: Each opponent may discard a card. If they don't, they lose 3 life. Repeat this process six more times.

Inundated Archive

This land enters tapped.
{T}: Add {U} or {B}.

Waterlogged Teachings

Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle.

Waterlogged Teachings // Inundated Archive

Shizo, Death's Storehouse

{T}: Add {B}.
{B}, {T}: Target legendary creature gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Toxic Deluge

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

Visions of Dread

Target opponent puts a creature card of their choice from their graveyard onto the battlefield under your control.
Flashback {8}{B}{B}. This spell costs {X} less to cast this way, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Siphon Insight

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Flashback {1}{U}{B}

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Undercity Sewers

({T}: Add {U} or {B}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

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.

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.

Command Tower

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

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.

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Glasspool Shore

Glasspool Mimic

You may have this creature enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Desertion

Counter target spell. If an artifact or creature spell is countered this way, put that card onto the battlefield under your control instead of into its owner's graveyard.

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Miscast

Counter target instant or sorcery spell unless its controller pays {3}.

Drowned Catacomb

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

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.

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.

Rapid Hybridization

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

Feed the Swarm

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

Sword of Once and Future

Equipped creature gets +2/+2 and has protection from blue and from black.
Whenever equipped creature deals combat damage to a player, surveil 2. Then you may cast an instant or sorcery spell with mana value 2 or less from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.
Equip {2}

See Double

This spell can't be copied.
Choose one. If an opponent has eight or more cards in their graveyard, you may choose both instead.
• Copy target spell. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)
• Create a token that's a copy of target creature.

Sunken Ruins

{T}: Add {C}.
{U/B}, {T}: Add {U}{U}, {U}{B}, or {B}{B}.

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Season of Weaving

Choose up to five {P} worth of modes. You may choose the same mode more than once.
{P} — Draw a card.
{P}{P} — Choose an artifact or creature you control. Create a token that's a copy of it.
{P}{P}{P} — Return each nonland, nontoken permanent to its owner's hand.

Hagra Broodpit

Hagra Mauling

This spell costs {1} less to cast if an opponent controls no basic lands.
Destroy target creature.

Hagra Mauling // Hagra Broodpit

Fell Mire

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Fell the Profane

Fell the Profane // Fell Mire

Malakir Mire

Malakir Rebirth

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Rebirth // Malakir Mire

Witch-king, Bringer of Ruin

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

Nuclear Fallout

Each creature gets twice -X/-X until end of turn. Each player gets X rad counters.

Darkwater Catacombs

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

Talisman of Dominance

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

Imp's Mischief

Change the target of target spell with a single target. You lose life equal to that spell's mana value.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Snap

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

Exotic Orchard

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

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}.

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.")

Consider

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

Cryptic Command

Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.

Have

High Fae Trickster

Flash (You may cast this spell any time you could cast an instant.)
Flying
You may cast spells as though they had flash.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle this card, create an X/X blue Shark creature token with flying.

Watery Grave

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

Ponder

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

Glorious Gale

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

Dark Ritual

Gloomlake Verge

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

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.

Underground River

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

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.

River of Tears

{T}: Add {U}. If you played a land this turn, add {B} instead.

Night's Whisper

Case of the Ransacked Lab

Instant and sorcery spells you cast cost {1} less to cast.
To solve — You've cast four or more instant and sorcery spells this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Whenever you cast an instant or sorcery spell, draw a card.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Cyber Conversion

Turn target creature face down. It's a 2/2 Cyberman artifact creature.

Counterspell

Archmage Emeritus

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

Reanimate

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

Castle Locthwain

This land enters tapped unless you control a Swamp.
{T}: Add {B}.
{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.

Bring the Ending

Counter target spell unless its controller pays {2}.
Corrupted — Counter that spell instead if its controller has three or more poison counters.

Fetid Pools

({T}: Add {U} or {B}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

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.)

Shipwreck Marsh

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

Lórien Revealed

Draw three cards.
Islandcycling {1} ({1}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Arcane Signet

Brainsurge

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

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Adaptive Training Post

Whenever you cast an instant or sorcery spell, if this artifact has fewer than three charge counters on it, put a charge counter on it.
Remove three charge counters from this artifact: When you next cast an instant or sorcery spell this turn, copy it and you may choose new targets for the copy.