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.

Silver Myr

Mechtitan Core

{5}, Exile Mechtitan Core and four other artifact creatures and/or Vehicles you control: Create Mechtitan, a legendary 10/10 Construct artifact creature token with flying, vigilance, trample, lifelink, and haste that's all colors. When that token leaves the battlefield, return all cards exiled with Mechtitan Core except Mechtitan Core to the battlefield tapped under their owners' control.
Crew 2

Thousand-Year Elixir

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

Lumbering Battlement

Vigilance
When Lumbering Battlement enters, exile any number of other nontoken creatures you control until it leaves the battlefield.
Lumbering Battlement gets +2/+2 for each card exiled with it.

Myr Propagator

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

Copper Myr

Iron Myr

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

Tribute Mage

When Tribute Mage enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

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.

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}.

Myr Galvanizer

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