Seat of the Synod

Hallowed Fountain

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

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.

Arcane Signet

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

Frogmyr Enforcer

Prototype {3}{R} — 2/2 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Myr Matrix

Indestructible (Effects that say "destroy" don't destroy this artifact.)
Myr creatures get +1/+1.
{5}: Create a 1/1 colorless Myr artifact creature token.

Lodestone Myr

Trample
Tap an untapped artifact you control: Lodestone Myr gets +1/+1 until end of turn.

Hovermyr

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Padeem, Consul of Innovation

Artifacts you control have hexproof. (They can't be the targets of spells or abilities your opponents control.)
At the beginning of your upkeep, if you control the artifact with the highest mana value or tied for the highest mana value, draw a card.

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.

Tempered Steel

Artifact creatures you control get +2/+2.

Counterspell

Dispatch

Tap target creature.
Metalcraft — If you control three or more artifacts, exile that creature.

Forest

Steel Overseer

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

Enlightened Tutor

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

Roaming Throne

Ward {2}
As Roaming Throne enters, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Plague Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{T}: Add {C}.

Plains

Etherium Sculptor

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

Myr Scrapling

Sacrifice Myr Scrapling: Put a +1/+1 counter on target creature.

Myr Kinsmith

When Myr Kinsmith enters, you may search your library for a Myr card, reveal it, put it into your hand, then shuffle.

Fellwar Stone

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

Island

Command Tower

Shimmer Dragon

Flying
As long as you control four or more artifacts, Shimmer Dragon has hexproof. (It can't be the target of spells or abilities your opponents control.)
Tap two untapped artifacts you control: Draw a card.

Alibou, Ancient Witness

Other artifact creatures you control have haste.
Whenever one or more artifact creatures you control attack, Alibou, Ancient Witness deals X damage to any target and you scry X, where X is the number of tapped artifacts you control.

Tezzeret, Master of the Bridge

Creature and planeswalker spells you cast have affinity for artifacts. (They cost {1} less to cast for each artifact you control.)
+2: Tezzeret, Master of the Bridge deals X damage to each opponent, where X is the number of artifacts you control. You gain X life.
−3: Return target artifact card from your graveyard to your hand.
−8: Exile the top ten cards of your library. Put all artifact cards from among them onto the battlefield.

Myr Galvanizer

Other Myr creatures you control get +1/+1.
{1}, {T}: Untap each other Myr you control.

Jhoira, Weatherlight Captain

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

Beast Within

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

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.

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Seized from Slumber

This spell costs {3} less to cast if it targets a tapped creature.
Destroy target creature.

Foundry Inspector

Patchwork Banner

As Patchwork Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{T}: Add one mana of any color.

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.)

Reliquary Tower

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

Myr Sire

When Myr Sire dies, create a 1/1 colorless Phyrexian Myr artifact creature token.

Teshar, Ancestor's Apostle

Flying
Whenever you cast a historic spell, return target creature card with mana value 3 or less from your graveyard to the battlefield. (Artifacts, legendaries, and Sagas are historic.)

Heroic Intervention

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

Razortide Bridge

Razortide Bridge enters tapped.
Indestructible
{T}: Add {W} or {U}.

Urtet, Remnant of Memnarch

Whenever you cast a Myr spell, create a 1/1 colorless Myr artifact creature token.
At the beginning of combat on your turn, untap each Myr you control.
{W}{U}{B}{R}{G}, {T}: Put three +1/+1 counters on each Myr you control. Activate only during your 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.

Organic Extinction

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Destroy all nonartifact creatures.

Copper Myr

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Ichorclaw Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Ichorclaw Myr becomes blocked, it gets +2/+2 until end of turn.

Great Furnace

Myr Superion

Spend only mana produced by creatures to cast this spell.

Myr Convert

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
{T}, Pay 2 life: Add one mana of any color.

Darkmoss Bridge

Darkmoss Bridge enters tapped.
Indestructible
{T}: Add {B} or {G}.

Palladium Myr

Inga and Esika

Creatures you control have vigilance and "{T}: Add one mana of any color. Spend this mana only to cast a creature spell."
Whenever you cast a creature spell, if three or more mana from creatures was spent to cast it, draw a card.

Knighted Myr

{2}{W}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on Knighted Myr, it gains double strike until end of turn.

Kindred Discovery

As Kindred Discovery enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Leaden Myr

Ancient Den

Adaptive Automaton

As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Sire of Seven Deaths

First strike, vigilance
Menace, trample
Reach, lifelink
Ward—Pay 7 life.

Sol Ring

Silver Myr

Unwinding Clock

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

Prop Room

Untap each creature you control during each other player's untap step.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Dazzling Theater

Creature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a creature spell pays for {1} or one mana of that creature's color.)
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Dazzling Theater // Prop Room

Iron Myr

Myrsmith

Whenever you cast an artifact spell, you may pay {1}. If you do, create a 1/1 colorless Myr artifact creature token.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Mountain

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.

Glimmervoid

At the beginning of the end step, if you control no artifacts, sacrifice Glimmervoid.
{T}: Add one mana of any color.

Darksteel Myr

Indestructible (Damage and effects that say "destroy" don't destroy this creature. If its toughness is 0 or less, it's still put into its owner's graveyard.)

Brudiclad, Telchor Engineer

Creature tokens you control have haste.
At the beginning of combat on your turn, create a 2/1 blue Phyrexian Myr artifact creature token. Then you may choose a token you control. If you do, each other token you control becomes a copy of that token.

Shimmer Myr

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

Lux Artillery

Whenever you cast an artifact creature spell, it gains sunburst. (It enters with a +1/+1 counter on it for each color of mana spent to cast it.)
At the beginning of your end step, if there are thirty or more counters among artifacts and creatures you control, Lux Artillery deals 10 damage to each opponent.

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Myr Enforcer

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)

Drossforge Bridge

Drossforge Bridge enters tapped.
Indestructible
{T}: Add {B} or {R}.

Myr Turbine

{T}: Create a 1/1 colorless Myr artifact creature token.
{T}, Tap five untapped Myr you control: Search your library for a Myr creature card, put it onto the battlefield, then shuffle.

Temple Garden

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

Gold Myr

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.)