Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.

Plundering Barbarian

When Plundering Barbarian enters, choose one —
• Smash the Chest — Destroy target artifact.
• Pry It Open — Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Combat Thresher

Prototype {2}{W} — 1/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Double strike
When Combat Thresher enters, draw a card.

Nahiri's Resolve

Creatures you control get +1/+0 and have haste.
At the beginning of your end step, exile any number of nontoken artifacts and/or creatures you control. Return those cards to the battlefield under their owner's control at the beginning of your next upkeep.

Devilish Valet

Trample, haste
Alliance — Whenever another creature you control enters, double Devilish Valet's power until end of turn.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Abdel Adrian, Gorion's Ward

When Abdel Adrian, Gorion's Ward enters, exile any number of other nonland permanents you control until Abdel Adrian leaves the battlefield. Create a 1/1 white Soldier creature token for each permanent exiled this way.
Choose a Background (You can have a Background as a second commander.)

Moonshaker Cavalry

Flying
When Moonshaker Cavalry enters, creatures you control gain flying and get +X/+X until end of turn, where X is the number of creatures you control.

Journey to Nowhere

When Journey to Nowhere enters, exile target creature.
When Journey to Nowhere leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.

Wall of Omens

Defender
When Wall of Omens enters, draw a card.

Arid Mesa

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

Prophetic Prism

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

Loran of the Third Path

Vigilance
When Loran of the Third Path enters, destroy up to one target artifact or enchantment.
{T}: You and target opponent each draw a card.

Prosperous Partnership

When Prosperous Partnership enters, create two 1/1 green and white Citizen creature tokens.
Tap three untapped creatures you control: Create a Treasure token.

Rugged Prairie

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

Dockside Extortionist

When Dockside Extortionist enters, create X Treasure tokens, where X is the number of artifacts and enchantments your opponents control. (Treasure tokens are artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Skyclave Apparition

When Skyclave Apparition enters, exile up to one target nonland, nontoken permanent you don't control with mana value 4 or less.
When Skyclave Apparition leaves the battlefield, the exiled card's owner creates an X/X blue Illusion creature token, where X is the mana value of the exiled card.

Boros Signet

Fiend Hunter

When Fiend Hunter enters, you may exile another target creature.
When Fiend Hunter leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. Battlefield Forge deals 1 damage to you.

Fellwar Stone

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

White Plume Adventurer

When White Plume Adventurer enters, you take the initiative.
At the beginning of each opponent's upkeep, untap a creature you control. If you've completed a dungeon, untap all creatures you control instead.

Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

Preston, the Vanisher

Whenever another nontoken creature you control enters, if it wasn't cast, create a token that's a copy of that creature, except it's a 0/1 white Illusion.
{1}{W}, Sacrifice five Illusions: Exile target nonland permanent.

Wily Goblin

When Wily Goblin enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Starlight Spectacular

Parade! — At the beginning of combat on your turn, choose creatures you control one at a time until each creature you control has been chosen. Each of those creatures gets +1/+1 until end of turn for each creature chosen before it. (Places everyone! The first creature in line gets +0/+0.)

Omen of the Sun

Flash
When Omen of the Sun enters, create two 1/1 white Human Soldier creature tokens and you gain 2 life.
{2}{W}, Sacrifice Omen of the Sun: Scry 2.

Rescue the Foal

Exile target creature you control, then return that card to the battlefield under its owner's control. (Then exile this card. You may cast the creature later from exile.)

Pegasus Guardian

Flying
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, create a 1/1 white Pegasus creature token with flying.

Pegasus Guardian // Rescue the Foal

Justiciar's Portal

Exile target creature you control, then return that card to the battlefield under its owner's control. It gains first strike until end of turn.

Mage's Attendant

When Mage's Attendant enters, create a 1/1 blue Wizard creature token with "{1}, Sacrifice this creature: Counter target noncreature spell unless its controller pays {1}."

Goblin Instigator

When Goblin Instigator enters, create a 1/1 red Goblin creature token.

Dawnbringer Cleric

When Dawnbringer Cleric enters, choose one —
• Cure Wounds — You gain 2 life.
• Dispel Magic — Destroy target enchantment.
• Gentle Repose — Exile target card from a graveyard.

Lae'zel's Acrobatics

Exile all nontoken creatures you control, then roll a d20.
1—9 | Return those cards to the battlefield under their owner's control at the beginning of the next end step.
10—20 | Return those cards to the battlefield under their owner's control, then exile them again. Return those cards to the battlefield under their owner's control at the beginning of the next end step.

Cloudshift

Exile target creature you control, then return that card to the battlefield under your control.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Hellkite Courser

Flying
When Hellkite Courser enters, you may put a commander you own from the command zone onto the battlefield. It gains haste. Return it to the command zone at the beginning of the next end step.

Icewind Stalwart

Protection Fighting Style — When Icewind Stalwart enters, exile up to one target non-Warrior creature you control, then return it to the battlefield under its owner's control.

Mountain

Resolute Reinforcements

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, create a 1/1 white Soldier creature token.

Arcane Signet

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

Clifftop Retreat

Clifftop Retreat enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Sundown Pass

Sundown Pass enters tapped unless you control two or more other lands.
{T}: Add {R} or {W}.

Street Urchin

Commander creatures you own have "{1}, Sacrifice another creature or an artifact: This creature deals 1 damage to any target."

Terror of the Peaks

Flying
Spells your opponents cast that target Terror of the Peaks cost an additional 3 life to cast.
Whenever another creature you control enters, Terror of the Peaks deals damage equal to that creature's power to any target.

Plains

Ardent Elementalist

When Ardent Elementalist enters, return target instant or sorcery card from your graveyard to your hand.

Oblivion Ring

When Oblivion Ring enters, exile another target nonland permanent.
When Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Sol Ring

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Thought Vessel

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

The Eternal Wanderer

No more than one creature can attack The Eternal Wanderer each combat.
+1: Exile up to one target artifact or creature. Return that card to the battlefield under its owner's control at the beginning of that player's next end step.
0: Create a 2/2 white Samurai creature token with double strike.
−4: For each player, choose a creature that player controls. Each player sacrifices all creatures they control not chosen this way.

Spectator Seating

Spectator Seating enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

Duergar Hedge-Mage

When Duergar Hedge-Mage enters, if you control two or more Mountains, you may destroy target artifact.
When Duergar Hedge-Mage enters, if you control two or more Plains, you may destroy target enchantment.

Exhibition Magician

When Exhibition Magician enters, choose one —
• Create a 1/1 green and white Citizen creature token.
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Scrollshift

Exile up to one target artifact, creature, or enchantment you control, then return it to the battlefield under its owner's control.
Draw a card.

Flicker of Fate

Exile target creature or enchantment, then return it to the battlefield under its owner's control.

Command Tower

Restoration Angel

Flash
Flying
When Restoration Angel enters, you may exile target non-Angel creature you control, then return that card to the battlefield under your control.

Sacred Peaks

({T}: Add {R} or {W}.)
Sacred Peaks enters tapped.

Acrobatic Maneuver

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

Solemn Simulacrum

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

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Éowyn, Fearless Knight

Haste
When Éowyn, Fearless Knight enters, exile target creature an opponent controls with greater power. Legendary creatures you control gain protection from each of that creature's colors until end of turn.

Alpine Meadow

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

Inspiring Overseer

Flying
When this creature enters, you gain 1 life and draw a card.

Relic of Legends

{T}: Add one mana of any color.
Tap an untapped legendary creature you control: Add one mana of any color.

Teleportation Circle

At the beginning of your end step, exile up to one target artifact or creature you control, then return that card to the battlefield under its owner's control.

Cursed Mirror

{T}: Add {R}.
As Cursed Mirror enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. Talisman of Conviction deals 1 damage to you.

Solitude

Flash
Lifelink
When Solitude enters, exile up to one other target creature. That creature's controller gains life equal to its power.
Evoke—Exile a white card from your hand.

Spirited Companion

When Spirited Companion enters, draw a card.

Sunbaked Canyon

{T}, Pay 1 life: Add {R} or {W}.
{1}, {T}, Sacrifice Sunbaked Canyon: Draw a card.

Fury

Double strike
When Fury enters, it deals 4 damage divided as you choose among any number of target creatures and/or planeswalkers.
Evoke—Exile a red card from your hand.