Myr Enforcer

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

Mountain

Skeleton Shard

{3}, {T} or {B}, {T}: Return target artifact creature card from your graveyard to your hand.

Leaden Myr

Frogmite

Ornithopter

Urza's Bauble

{T}, Sacrifice this artifact: Look at a card at random in target player's hand. You draw a card at the beginning of the next turn's upkeep.

Feedback Bolt

Feedback Bolt deals damage to target player or planeswalker equal to the number of artifacts you control.

Irradiate

Target creature gets -1/-1 until end of turn for each artifact you control.

Mishra's Bauble

{T}, Sacrifice this artifact: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Nim Shambler

This creature gets +1/+0 for each artifact you control.
Sacrifice a creature: Regenerate this creature.

Welding Jar

Sacrifice this artifact: Regenerate target artifact.

Dross Golem

Affinity for Swamps (This spell costs {1} less to cast for each Swamp you control.)
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Nim Shrieker

Flying
This creature gets +1/+0 for each artifact you control.

Vermiculos

Whenever an artifact enters, this creature gets +4/+4 until end of turn.

Swamp

Myr Servitor

At the beginning of your upkeep, if this creature is on the battlefield, each player returns all cards named Myr Servitor from their graveyard to the battlefield.

Hunger of the Nim

Target creature gets +1/+0 until end of turn for each artifact you control.

Nim Lasher

This creature gets +1/+0 for each artifact you control.

Conjurer's Bauble

{T}, Sacrifice this artifact: Put up to one target card from your graveyard on the bottom of your library. Draw a card.

Smokestack

At the beginning of your upkeep, you may put a soot counter on this artifact.
At the beginning of each player's upkeep, that player sacrifices a permanent of their choice for each soot counter on this artifact.

Darksteel Citadel

Great Furnace

Have

Phyrexian Walker

Don't Have

Cranial Plating

Equipped creature gets +1/+0 for each artifact you control.
{B}{B}: Attach this Equipment to target creature you control.
Equip {1}

Vault of Whispers

Vorrac Battlehorns

Equipped creature has trample and can't be blocked by more than one creature.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)