Mirrodin Besieged

As this enchantment enters, choose Mirran or Phyrexian.
• Mirran — Whenever you cast an artifact spell, create a 1/1 colorless Myr artifact creature token.
• Phyrexian — At the beginning of your end step, draw a card, then discard a card. Then if there are fifteen or more artifact cards in your graveyard, target opponent loses the game.

Monumental Corruption

Target player draws X cards and loses X life, where X is the number of artifacts you control.

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.

Baylen, the Haymaker

Tap two untapped tokens you control: Add one mana of any color.
Tap three untapped tokens you control: Draw a card.
Tap four untapped tokens you control: Put three +1/+1 counters on Baylen. It gains trample until end of turn.

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.

Cryptolith Rite

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

Three Tree Mascot

Changeling (This card is every creature type.)
{1}: Add one mana of any color. Activate only once each turn.

Myr Welder

Imprint — {T}: Exile target artifact card from a graveyard.
This creature has all activated abilities of all cards exiled with it.

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. This land deals 1 damage to you.

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Mountain

Battle at the Bridge

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Target creature gets -X/-X until end of turn. You gain X life.

Tomb of the Spirit Dragon

{T}: Add {C}.
{2}, {T}: You gain 1 life for each colorless creature you control.

Delete

Delete deals X damage to each nonartifact creature and each player.

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

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.

Inventors' Fair

At the beginning of your upkeep, if you control three or more artifacts, you gain 1 life.
{T}: Add {C}.
{4}, {T}, Sacrifice Inventors' Fair: Search your library for an artifact card, reveal it, put it into your hand, then shuffle. Activate only if you control three or more artifacts.

Kindred Discovery

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

Island

Arcane Sanctum

This land enters tapped.
{T}: Add {W}, {U}, or {B}.

Song of Freyalise

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III — Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.

March of Progress

Choose target artifact creature you control. For each creature chosen this way, create a token that's a copy of it.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change its text by replacing all instances of "target" with "each.")

Myr Enforcer

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

Palladium Myr

Jhoira, Weatherlight Captain

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

Enduring Vitality

Vigilance
Creatures you control have "{T}: Add one mana of any color."
When Enduring Vitality dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Foreboding Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Swamp, Forest, or Island card, put it onto the battlefield tapped, then shuffle.
Cycling {B}{G}{U} ({B}{G}{U}, Discard this card: Draw a card.)

Realmwalker

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Etherium Sculptor

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

Alibou, Ancient Witness

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

Myr Propagator

{3}, {T}: Create a token that's a copy of this creature.

Swamp

Genesis Chamber

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

Clock of Omens

Tap two untapped artifacts you control: Untap target artifact.

Uncharted Haven

This land enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Dispatch

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

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.)

Savage Lands

This land enters tapped.
{T}: Add {B}, {R}, or {G}.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Hammer of Purphoros

Creatures you control have haste.
{2}{R}, {T}, Sacrifice a land: Create a 3/3 colorless Golem enchantment artifact creature token.

Meria, Scholar of Antiquity

Tap an untapped nontoken artifact you control: Add {G}.
Tap two untapped nontoken artifacts you control: Exile the top card of your library. You may play it this turn.

Myr Galvanizer

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

Tezzeret the Seeker

+1: Untap up to two target artifacts.
−X: Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.
−5: Artifacts you control become artifact creatures with base power and toughness 5/5 until end of turn.

Lodestone Myr

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

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Sol Ring

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. This land deals 1 damage to you.

The Mycosynth Gardens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{X}, {T}: This land becomes a copy of target nontoken artifact you control with mana value X.

Elven Chorus

You may look at the top card of your library any time.
You may cast creature spells from the top of your library.
Creatures you control have "{T}: Add one mana of any color."

Myr Kinsmith

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

Wake the Past

Return all artifact cards from your graveyard to the battlefield. They gain haste until end of turn.

Pact of the Serpent

Choose a creature type. Target player draws X cards and loses X life, where X is the number of creatures they control of the chosen type.

Seething Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.
Cycling {U}{B}{R} ({U}{B}{R}, Discard this card: Draw a card.)

Bloodline Pretender

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on this creature.

Vindicate

Copper Myr

Thought Monitor

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When this creature enters, draw two cards.

Myr Reservoir

{T}: Add {C}{C}. Spend this mana only to cast Myr spells or activate abilities of Myr.
{3}, {T}: Return target Myr card from your graveyard to your hand.

Leaden Myr

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Insatiable Avarice

Spree (Choose one or more additional costs.)
+ {2} — Search your library for a card, then shuffle and put that card on top.
+ {B}{B} — Target player draws three cards and loses 3 life.

Shalai and Hallar

Flying, vigilance
Whenever one or more +1/+1 counters are put on a creature you control, Shalai and Hallar deals that much damage to target opponent.

Myr Sire

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

Iron Myr

Command Tower

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

Timeless Lotus

Timeless Lotus enters tapped.
{T}: Add {W}{U}{B}{R}{G}.

Fomori Vault

{T}: Add {C}.
{3}, {T}, Discard a card: Look at the top X cards of your library, where X is the number of artifacts you control. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Perilous Myr

When this creature dies, it deals 2 damage to any target.

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.

Adarkar Wastes

{T}: Add {C}.
{T}: Add {W} or {U}. This land deals 1 damage to you.

Opposition

Tap an untapped creature you control: Tap target artifact, creature, or land.

Myr Retriever

When this creature dies, return another target artifact card from your graveyard to your hand.

Thoughtcast

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

Myr Scrapling

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

Jegantha, the Wellspring

Companion — No card in your starting deck has more than one of the same mana symbol in its mana cost. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
{T}: Add {W}{U}{B}{R}{G}. This mana can't be spent to pay generic mana costs.

Opulent Palace

This land enters tapped.
{T}: Add {B}, {G}, or {U}.

Plains

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. This land deals 1 damage to you.

Myr Superion

Spend only mana produced by creatures to cast this spell.

Myr Battlesphere

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

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.

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice this artifact: Create a 10/10 colorless Eldrazi creature token.

Urza's Incubator

As this artifact enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Crib Swap

Changeling (This card is every creature type.)
Exile target creature. Its controller creates a 1/1 colorless Shapeshifter creature token with changeling.

Sandsteppe Citadel

This land enters tapped.
{T}: Add {W}, {B}, or {G}.

Alloy Myr

Caves of Koilos

{T}: Add {C}.
{T}: Add {W} or {B}. This land deals 1 damage to you.

Thopter Engineer

When this creature enters, create a 1/1 colorless Thopter artifact creature token with flying.
Artifact creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

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}.

Silver Myr

Mirran Spy

Flying
Whenever you cast an artifact spell, you may untap target creature.

Nomad Outpost

This land enters tapped.
{T}: Add {R}, {W}, or {B}.

Shimmer Dragon

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

Battery Bearer

Creatures you control have "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell."
Whenever you cast an artifact spell with mana value 6 or greater, draw a card.

Forest

Contaminated Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle.
Cycling {W}{U}{B} ({W}{U}{B}, Discard this card: Draw a card.)

Seaside Citadel

This land enters tapped.
{T}: Add {G}, {W}, or {U}.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Gold Myr

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.)

Cascading Cataracts

Indestructible
{T}: Add {C}.
{5}, {T}: Add five mana in any combination of colors.