Durnan of the Yawning Portal

Whenever Durnan attacks, look at the top four cards of your library. You may exile a creature card from among them. Put the rest on the bottom of your library in any order. For as long as that card remains exiled, you may cast it. That spell has undaunted. (It costs {1} less to cast for each opponent.)
Choose a Background (You can have a Background as a second commander.)

Drix Fatemaker

When this creature enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample.
Warp {1}{G} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Arcane Signet

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

Loan Shark

When this creature enters, if you've cast two or more spells this turn, draw a card.
Plot {3}{U} (You may pay {3}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Doc Aurlock, Grizzled Genius

Spells you cast from your graveyard or from exile cost {2} less to cast.
Plotting cards from your hand costs {2} less.

Slickshot Lockpicker

When this creature enters, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)
Plot {2}{U} (You may pay {2}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Forest

Island

Arrogant Wurm

Trample
Madness {2}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Hinterland Harbor

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

Visage Bandit

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.
Plot {2}{U} (You may pay {2}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Djinn of Fool's Fall

Flying
Plot {3}{U} (You may pay {3}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Lifestream's Blessing

Draw X cards, where X is the greatest power among creatures you controlled as you cast this spell. If this spell was cast from exile, you gain twice X life.
Foretell {4}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Savvy Trader

When this creature enters, exile target permanent card from your graveyard. You may play that card for as long as it remains exiled.
Spells you cast from anywhere other than your hand cost {1} less to cast.

Scale Deflection

Put two +1/+1 counters on target creature and untap it. It gains hexproof until end of turn. (Then exile this card. You may cast the creature later from exile.)

Dread Linnorm

This creature can't be blocked by creatures with power 3 or less.

Dread Linnorm // Scale Deflection

Outcaster Trailblazer

When this creature enters, add one mana of any color.
Whenever another creature you control with power 4 or greater enters, draw a card.
Plot {2}{G} (You may pay {2}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Neerdiv, Devious Diver

Whenever Neerdiv becomes tapped, target player mills cards equal to its power.
Whenever you cast a spell from your graveyard or activate an ability of a card in your graveyard, draw a card and put a +1/+1 counter on Neerdiv.

Counterspell

Green Slime

Flash
When this creature enters, counter target activated or triggered ability from an artifact or enchantment source. If a permanent's ability is countered this way, destroy that permanent.
Foretell {G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Semblance Anvil

Imprint — When this artifact enters, you may exile a nonland card from your hand.
Spells you cast that share a card type with the exiled card cost {2} less to cast.

Battle Mammoth

Trample
Whenever a permanent you control becomes the target of a spell or ability an opponent controls, you may draw a card.
Foretell {2}{G}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Make Your Own Luck

Look at the top three cards of your library. You may exile a nonland card from among them. If you do, it becomes plotted. Put the rest into your hand. (You may cast it as a sorcery on a later turn without paying its mana cost.)

Dreamroot Cascade

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

Anticausal Vestige

When this creature leaves the battlefield, draw a card, then you may put a permanent card with mana value less than or equal to the number of lands you control from your hand onto the battlefield tapped.
Warp {4} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Botanical Sanctum

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

Spinewoods Paladin

Trample
When this creature enters, you gain 3 life.
Plot {3}{G} (You may pay {3}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Bear Down

Destroy target artifact or enchantment. (Then exile this card. You may cast the creature later from exile.)

Stormkeld Vanguard

This creature can't be blocked by creatures with power 2 or less.

Stormkeld Vanguard // Bear Down

Sage of the Beyond

Flying
Spells you cast from anywhere other than your hand cost {2} less to cast.
Foretell {4}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Tail the Suspect

Investigate. You may play an additional land this turn. (Then exile this card. You may cast the creature later from exile.)

Kellan, Inquisitive Prodigy

Flying, vigilance
Whenever Kellan attacks, destroy up to one target artifact. If you controlled that permanent, draw a card.

Kellan, Inquisitive Prodigy // Tail the Suspect

The Thirteenth Doctor

Paradox — Whenever you cast a spell from anywhere other than your hand, put a +1/+1 counter on target creature.
Team TARDIS — At the beginning of your end step, untap each creature you control with a counter on it.

Lucky Clover

Whenever you cast an Adventure instant or sorcery spell, copy it. You may choose new targets for the copy.

Fertile Footsteps

Search your library for a basic land card, put it onto the battlefield, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Beanstalk Giant

Beanstalk Giant's power and toughness are each equal to the number of lands you control.

Beanstalk Giant // Fertile Footsteps

Marang River Prowler

This creature can't block and can't be blocked.
You may cast this card from your graveyard as long as you control a black or green permanent.

Aloe Alchemist

Trample
When this card becomes plotted, target creature gets +3/+2 and gains trample until end of turn.
Plot {1}{G} (You may pay {1}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Cosmos Charger

Flash
Flying
Foretelling cards from your hand costs {1} less and can be done on any player's turn.
Foretell {2}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Capsizing Wave

Return target creature to its owner's hand. (Then exile this card. You may cast the creature later from exile.)

Sword Coast Serpent

This creature can't be blocked as long as you've cast a noncreature spell this turn.

Sword Coast Serpent // Capsizing Wave

Vineglimmer Snarl

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

Fblthp, Lost on the Range

Ward {2}
You may look at the top card of your library any time.
The top card of your library has plot. The plot cost is equal to its mana cost.
You may plot nonland cards from the top of your library.

Rootcoil Creeper

{T}: Add one mana of any color.
{T}: Add two mana of any one color. Spend this mana only to cast spells from your graveyard.
{G}{U}, {T}, Exile this creature: Return target card with flashback you own from exile to your hand.

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.

Cultivate

The Foretold Soldier

This creature must be blocked if able.
This creature can't be blocked by more than one creature.
Whenever this creature deals damage, exile it face down. It becomes foretold.
Foretell {1}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Temple of Mystery

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {G} or {U}.

Railway Brawler

Reach, trample
Whenever another creature you control enters, put X +1/+1 counters on it, where X is its power.
Plot {3}{G} (You may pay {3}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Broodguard Elite

This creature enters with X +1/+1 counters on it.
When this creature leaves the battlefield, put its counters on target creature you control.
Warp {X}{G} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Sol Ring

Rejuvenating Springs

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

Command Tower

Saw It Coming

Counter target spell.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Breeding Pool

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

Misty Rainforest

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