Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Captivating Crew

{3}{R}: Gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn. Activate only as a sorcery.

Besmirch

Until end of turn, gain control of target creature and it gains haste. Untap and goad that creature. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Combustible Gearhulk

First strike
When Combustible Gearhulk enters, target opponent may have you draw three cards. If the player doesn't, you mill three cards, then Combustible Gearhulk deals damage to that player equal to the total mana value of those cards.

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Ashnod's Altar

Relic Vial

{2}, {T}, Sacrifice a creature: Draw a card.
As long as you control a Cleric, Relic Vial has "Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life."

Circuit Mender

When Circuit Mender enters, you gain 2 life.
When Circuit Mender leaves the battlefield, draw a card.

Marble Diamond

Marble Diamond enters tapped.
{T}: Add {W}.

Spirited Companion

When Spirited Companion enters, draw a card.

Mountain

Makeshift Munitions

{1}, Sacrifice an artifact or creature: Makeshift Munitions deals 1 damage to any target.

Threaten

Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn. (It can attack and {T} this turn.)

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.

Traitorous Greed

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Add two mana of any one color. (The creature can attack and {T} this turn.)

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.)

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Temple of Triumph

Temple of Triumph enters tapped.
When Temple of Triumph enters, scry 1.
{T}: Add {R} or {W}.

Barrage of Expendables

{R}, Sacrifice a creature: Barrage of Expendables deals 1 damage to any target.

Bloody Betrayal

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Knight of the White Orchid

First strike
When Knight of the White Orchid enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Sol Ring

Coldsteel Heart

Coldsteel Heart enters tapped.
As Coldsteel Heart enters, choose a color.
{T}: Add one mana of the chosen color.

Traitorous Blood

Gain control of target creature until end of turn. Untap it. It gains trample and haste until end of turn.

Hazoret's Favor

At the beginning of combat on your turn, you may have target creature you control get +2/+0 and gain haste until end of turn. If you do, sacrifice it at the beginning of the next end step.

Alpine Meadow

({T}: Add {R} or {W}.)
Alpine Meadow enters tapped.

Wrangle

Gain control of target creature with power 4 or less until end of turn. Untap that creature. It gains haste until end of turn.

Portent of Betrayal

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Shackles of Treachery

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gains haste and "Whenever this creature deals damage, destroy target Equipment attached to it."

Port Razer

Whenever Port Razer deals combat damage to a player, untap each creature you control. After this phase, there is an additional combat phase.
Port Razer can't attack a player it has already attacked this turn.

Inspiring Overseer

Flying
When Inspiring Overseer enters, you gain 1 life and draw a card.

Spawning Pit

Sacrifice a creature: Put a charge counter on Spawning Pit.
{1}, Remove two charge counters from Spawning Pit: Create a 2/2 colorless Spawn artifact creature token.

Boros Garrison

Boros Garrison enters tapped.
When Boros Garrison enters, return a land you control to its owner's hand.
{T}: Add {R}{W}.

Phyrexian Vault

{2}, {T}, Sacrifice a creature: Draw a card.

Fire Diamond

Fire Diamond enters tapped.
{T}: Add {R}.

Glittering Stockpile

{T}: Add {R}. Put a stash counter on Glittering Stockpile.
{T}, Sacrifice Glittering Stockpile: Add X mana of any one color, where X is the number of stash counters on Glittering Stockpile.

Helm of Awakening

Martyr's Cause

Sacrifice a creature: The next time a source of your choice would deal damage to any target this turn, prevent that damage.

Inherited Envelope

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

Mark of Mutiny

Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn. (It can attack and {T} this turn.)

Claim the Firstborn

Gain control of target creature with mana value 3 or less until end of turn. Untap that creature. It gains haste until end of turn.

Letter of Acceptance

{T}: Add one mana of any color.
{2}, {T}, Sacrifice Letter of Acceptance: Draw a card.

Loyal Warhound

Vigilance
When Loyal Warhound enters, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Hijack

Gain control of target artifact or creature until end of turn. Untap it. It gains haste until end of turn.

Culling Dais

{T}, Sacrifice a creature: Put a charge counter on Culling Dais.
{1}, Sacrifice Culling Dais: Draw a card for each charge counter on Culling Dais.

Bloodthirster

Flying, trample
Whenever Bloodthirster deals combat damage to a player, untap it. After this phase, there is an additional combat phase.
Bloodthirster can't attack a player it has already attacked this turn.

Evolving Wilds

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

Lorehold Campus

Lorehold Campus enters tapped.
{T}: Add {R} or {W}.
{4}, {T}: Scry 1.

Traitorous Instinct

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gets +2/+0 and gains haste.

Twisted Fealty

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.
Create a Wicked Role token attached to up to one target creature. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1. When this Aura is put into a graveyard, each opponent loses 1 life.)

Goblin Bombardment

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

Duke Ulder Ravengard

At the beginning of combat on your turn, another target creature you control gains haste and myriad until end of turn. (Whenever it 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.)

Aurelia, the Warleader

Flying, vigilance, haste
Whenever Aurelia, the Warleader attacks for the first time each turn, untap all creatures you control. After this phase, there is an additional combat phase.

Star Compass

Star Compass enters tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Plains

The Akroan War

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Gain control of target creature for as long as The Akroan War remains on the battlefield.
II — Until your next turn, creatures your opponents control attack each combat if able.
III — Each tapped creature deals damage to itself equal to its power.

Guardian Idol

Guardian Idol enters tapped.
{T}: Add {C}.
{2}: Guardian Idol becomes a 2/2 Golem artifact creature until end of turn.

Agrus Kos, Eternal Soldier

Vigilance
Whenever Agrus Kos, Eternal Soldier becomes the target of an ability that targets only it, you may pay {1}{R/W}. If you do, copy that ability for each other creature you control that ability could target. Each copy targets a different one of those creatures. ({R/W} can be paid with either {R} or {W}.)

Combat Celebrant

If Combat Celebrant hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)