Karlach, Fury of Avernus

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase.
Choose a Background (You can have a Background as a second commander.)

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Elvish Mystic

Sol Ring

Command Tower

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

Arcane Signet

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Island

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Nalfeshnee

Flying
Whenever you cast a spell from exile, copy it. You may choose new targets for the copy. If it's a permanent spell, the copy gains haste and "At the beginning of the end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)

Reliquary Tower

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

Bloodstained Mire

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

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.

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Fyndhorn Elves

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Pako, Arcane Retriever

Partner with Haldan, Avid Arcanist
Haste
Whenever Pako attacks, exile the top card of each player's library and put a fetch counter on each of them. Put a +1/+1 counter on Pako for each noncreature card exiled this way.

Negate

Beast Within

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

Frantic Search

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

Lightning Greaves

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

Rapid Hybridization

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

Dispel

The Reaver Cleaver

Equipped creature gets +1/+1 and has trample and "Whenever this creature deals combat damage to a player or planeswalker, create that many Treasure tokens."
Equip {3}

Seedtime

Cast this spell only during your turn.
Take an extra turn after this one if an opponent cast a blue spell this turn.

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.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Memory Lapse

Counter target spell. If that spell is countered this way, put it on top of its owner's library instead of into that player's graveyard.

Winged Boots

Equipped creature has flying and ward {4}. (Whenever equipped creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)
Equip {1}

Temporal Mastery

Take an extra turn after this one. Exile Temporal Mastery.
Miracle {1}{U} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Cultivate

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.

Haldan, Avid Arcanist

Partner with Pako, Arcane Retriever (When this creature enters, target player may put Pako into their hand from their library, then shuffle.)
You may play lands and cast noncreature spells from among cards you exiled that have fetch counters on them, and you may spend mana as though it were mana of any color to cast those spells.

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.")

Sakura-Tribe Elder

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

Rishkar's Expertise

Draw cards equal to the greatest power among creatures you control.
You may cast a spell with mana value 5 or less from your hand without paying its mana cost.

Kodama's Reach

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.

Moraug, Fury of Akoum

Each creature you control gets +1/+0 for each time it has attacked this turn.
Landfall — Whenever a land you control enters, if it's your main phase, there's an additional combat phase after this phase. At the beginning of that combat, untap all creatures you control.

Birds of Paradise

Wild-Magic Sorcerer

The first spell you cast from exile each turn has cascade. (When you cast your first spell from exile, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Llanowar Elves

Mystical Tutor

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

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Personal Tutor

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

Rampant Growth

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

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Fabled Passage

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

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.

Temporal Manipulation

Rogue's Passage

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

Mountain

Summer Bloom

You may play up to three additional lands this turn.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Pongify

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

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Plargg and Nassari

At the beginning of your upkeep, each player exiles cards from the top of their library until they exile a nonland card. An opponent chooses a nonland card exiled this way. You may cast up to two spells from among the other cards exiled this way without paying their mana costs.

Time Warp

Target player takes an extra turn after this one.

Tireless Provisioner

Landfall — Whenever a land you control enters, create a Food token or a Treasure token. (Food is an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life." Treasure is an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Seize the Day

Untap target creature. After this main phase, there is an additional combat phase followed by an additional main phase.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Counterspell

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Expel from Orazca

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Return target nonland permanent to its owner's hand. If you have the city's blessing, you may put that permanent on top of its owner's library instead.

Harrow

As an additional cost to cast this spell, sacrifice a land.
Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Exploration

You may play an additional land on each of your turns.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Forest

Keeper of Secrets

First strike, haste
Symphony of Pain — Whenever you cast a spell from anywhere other than your hand, this creature deals damage equal to that spell's mana value to target opponent.