Etched Champion

Metalcraft — This creature has protection from each color as long as you control three or more artifacts.

Welding Jar

Sacrifice this artifact: Regenerate target artifact.

Thoughtcast

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

Steel Overseer

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

Vault Skirge

({B/P} can be paid with either {B} or 2 life.)
Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Cranial Plating

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

Frogmite

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

Seat of the Synod

Myr Enforcer

Ornithopter

Vault of Whispers

Tolarian Academy

{T}: Add {U} for each artifact you control.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Master of Etherium

Master of Etherium's power and toughness are each equal to the number of artifacts you control.
Other artifact creatures you control get +1/+1.

Glimmervoid

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

Ancient Den

Baleful Strix

Flying, deathtouch
When this creature enters, draw a card.

Signal Pest

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
This creature can't be blocked except by creatures with flying or reach.

Slate of Ancestry

{4}, {T}, Discard your hand: Draw a card for each creature you control.

Dispatch

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