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.

Island

Mystic Monastery

Mystic Monastery enters tapped.
{T}: Add {U}, {R}, or {W}.

Shore Up

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak, Glory Dominus. ({W/P} can be paid with either {W} or 2 life.)

Cascade Bluffs

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

Temple of Enlightenment

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

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Wizard Class

(Gain the next level as a sorcery to add its ability.)
You have no maximum hand size.
{2}{U}: Level 2
When this Class becomes level 2, draw two cards.
{4}{U}: Level 3
Whenever you draw a card, put a +1/+1 counter on target creature you control.

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)

Battlefield Forge

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

Agate Instigator

Offspring {1}{R} (You may pay an additional {1}{R} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Scrap Trawler

Whenever Scrap Trawler or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

Eaten by Piranhas

Flash
Enchant creature
Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Silver Myr

Generous Gift

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

Clifftop Retreat

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

Gold Myr

Ornithopter of Paradise

The Reality Chip

You may look at the top card of your library any time.
As long as The Reality Chip is attached to a creature, you may play lands and cast spells from the top of your library.
Reconfigure {2}{U} ({2}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Arcane Signet

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

Skycloud Expanse

Wurmcoil Engine

Deathtouch, lifelink
When Wurmcoil Engine dies, create a 3/3 colorless Phyrexian Wurm artifact creature token with deathtouch and a 3/3 colorless Phyrexian Wurm artifact creature token with lifelink.

Sai, Master Thopterist

Whenever you cast an artifact spell, create a 1/1 colorless Thopter artifact creature token with flying.
{1}{U}, Sacrifice two artifacts: Draw a card.

Steel Overseer

{T}: Put a +1/+1 counter on each artifact creature you control.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Mycosynth Golem

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Artifact creature spells you cast have affinity for artifacts. (They cost {1} less to cast for each artifact you control.)

Evolving Wilds

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

Canoptek Scarab Swarm

Flying
Feeder Mandibles — When Canoptek Scarab Swarm enters, exile target player's graveyard. For each artifact or land card exiled this way, create a 1/1 colorless Insect artifact creature token with flying.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your hand.

Terramorphic Expanse

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

Plains

Reckless Fireweaver

Whenever an artifact you control enters, Reckless Fireweaver deals 1 damage to each opponent.

Ferrous Lake

Palladium Myr

Castle Ardenvale

Castle Ardenvale enters tapped unless you control a Plains.
{T}: Add {W}.
{2}{W}{W}, {T}: Create a 1/1 white Human creature token.

Seachrome Coast

Seachrome Coast enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

Sol Ring

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}

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.

Jhoira, Weatherlight Captain

Whenever you cast a historic spell, draw a card. (Artifacts, legendaries, and Sagas are historic.)

Caretaker's Talent

(Gain the next level as a sorcery to add its ability.)
Whenever one or more tokens you control enter, draw a card. This ability triggers only once each turn.
{W}: Level 2
When this Class becomes level 2, create a token that's a copy of target token you control.
{3}{W}: Level 3
Creature tokens you control get +2/+2.

Adarkar Wastes

{T}: Add {C}.
{T}: Add {W} or {U}. Adarkar Wastes deals 1 damage to you.

Temple of Epiphany

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

Helm of Awakening

Command Tower

Counterspell

Mountain

Panharmonicon

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

Pull from Tomorrow

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Dawn's Truce

Gift a card (You may promise an opponent a gift as you cast this spell. If you do, they draw a card before its other effects.)
You and permanents you control gain hexproof until end of turn. If the gift was promised, permanents you control also gain indestructible until end of turn.

Azorius Signet

Exotic Orchard

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

Sharding Sphinx

Flying
Whenever an artifact creature you control deals combat damage to a player, you may create a 1/1 blue Thopter artifact creature token with flying.

Urza, Lord High Artificer

When Urza, Lord High Artificer enters, create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."
Tap an untapped artifact you control: Add {U}.
{5}: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost.

Angel of the Ruins

Flying
When Angel of the Ruins enters, exile up to two target artifacts and/or enchantments.
Plainscycling {2} ({2}, Discard this card: Search your library for a Plains card, reveal it, put it into your hand, then shuffle.)

Cybermen Squadron

Nonlegendary artifact creatures you control have myriad. (Whenever a creature with myriad 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.)

Trading Post

{1}, {T}, Discard a card: You gain 4 life.
{1}, {T}, Pay 1 life: Create a 0/1 white Goat creature token.
{1}, {T}, Sacrifice a creature: Return target artifact card from your graveyard to your hand.
{1}, {T}, Sacrifice an artifact: Draw a card.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Zinnia, Valley's Voice

Flying
Zinnia, Valley's Voice gets +X/+0, where X is the number of other creatures you control with base power 1.
Creature spells you cast have offspring {2}. (You may pay an additional {2} as you cast a creature spell. If you do, when that creature enters, create a 1/1 token copy of it.)

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Myr Battlesphere

When Myr Battlesphere enters, create four 1/1 colorless Myr artifact creature tokens.
Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Curiosity Crafter

Flying
You have no maximum hand size.
Whenever a creature token you control deals combat damage to a player, draw a card.

Storm of Souls

Return all creature cards from your graveyard to the battlefield. Each of them is a 1/1 Spirit with flying in addition to its other types. Exile Storm of Souls.

Enthusiastic Mechanaut

Flying
Artifact spells you cast cost {1} less to cast.

Temple of Triumph

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

Etherium Sculptor

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

Izzet Signet

Shimmer Myr

Flash
You may cast artifact spells as though they had flash.

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. Shivan Reef deals 1 damage to you.

Unwinding Clock

Untap all artifacts you control during each other player's untap step.

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Darksteel Forge

Artifacts you control have indestructible. (Effects that say "destroy" don't destroy them. Artifact creatures with indestructible can't be destroyed by damage.)

Junk Diver

Flying
When Junk Diver dies, return another target artifact card from your graveyard to your hand.

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Boros Signet

Rugged Prairie

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

Sunscorched Divide

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Foundry Inspector

Iron Myr

Workshop Assistant

When Workshop Assistant dies, return another target artifact card from your graveyard to your hand.

Circuit Mender

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