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.

Snow-Covered Mountain

All Will Be One

Whenever you put one or more counters on a permanent or player, All Will Be One deals that much damage to target opponent, creature an opponent controls, or planeswalker an opponent controls.

Vault of Whispers

Command Tower

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

Tree of Tales

Reflections of Littjara

As Reflections of Littjara enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

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.

Myr Galvanizer

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

Parcel Myr

Ancient Den

Silver Myr

Have

Shimmer Myr

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

Darksteel Citadel

Myrsmith

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

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

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.

Snow-Covered Swamp

Palladium Myr

Myr Propagator

{3}, {T}: Create a token that's a copy of Myr Propagator.

Kindred Summons

Choose a creature type. Reveal cards from the top of your library until you reveal X creature cards of the chosen type, where X is the number of creatures you control of that type. Put those cards onto the battlefield, then shuffle the rest of the revealed cards into your library.

Great Furnace

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.

Myr Quadropod

{3}: Switch Myr Quadropod's power and toughness until end of turn.

Mirrodin Besieged

As Mirrodin Besieged 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.

Snow-Covered Island

Snow-Covered Plains

Perilous Myr

When Perilous Myr dies, it deals 2 damage to any target.

Simic Ascendancy

{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on Simic Ascendancy.
At the beginning of your upkeep, if Simic Ascendancy has twenty or more growth counters on it, you win the game.

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.

Alloy Myr

Myr Custodian

When Myr Custodian enters, scry 2. Then each opponent may scry 1. (To scry X, a player looks at the top X cards of their library, then puts any number of them on the bottom and the rest on top in any order.)

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.)

Sarcomite Myr

{2}: Sarcomite Myr gains flying until end of turn.
{2}, Sacrifice Sarcomite Myr: Draw a card.

Myr Retriever

When Myr Retriever dies, return another target artifact card from your graveyard to your hand.

Copper Myr

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.

Cryptolith Rite

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

Iron Myr

Hovermyr

Myr Kinsmith

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

Holy Frazzle-Cannon

Whenever equipped creature attacks, put a +1/+1 counter on that creature and each other creature you control that shares a creature type with it.
Equip {1}

Invasion of New Capenna

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of New Capenna enters, you may sacrifice an artifact or creature. When you do, exile target artifact or creature an opponent controls.

Invasion of New Capenna // Holy Frazzle-Cannon

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Mechanized Production

Enchant artifact you control
At the beginning of your upkeep, create a token that's a copy of enchanted artifact. Then if you control eight or more artifacts with the same name as one another, you win the game.

Leaden Myr

Gold Myr

Seat of the Synod

Myr Sire

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

Snow-Covered Forest

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.