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.

Cranial Plating

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

Glimmervoid

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

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.

Signal Pest

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

Ornithopter

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.)

Ancient Den

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.

Slate of Ancestry

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

Etched Champion

Metalcraft — Etched Champion has protection from all colors as long as you control three or more artifacts.

Myr Enforcer

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

Vault of Whispers

Dispatch

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