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.

Plains

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Leonin Squire

When Leonin Squire enters, return target artifact card with mana value 1 or less from your graveyard to your hand.

Leonin Abunas

Artifacts you control have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Etherium Sculptor

Artifact spells you cast cost {1} less to cast.

Retract

Return all artifacts you control to their owner's hand.

Leonin Elder

Whenever an artifact enters, you may gain 1 life.

Clockwork Beetle

Clockwork Beetle enters with two +1/+1 counters on it.
Whenever Clockwork Beetle attacks or blocks, remove a +1/+1 counter from it at end of combat.

Arcbound Worker

Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Retaliate

Destroy all creatures that dealt damage to you this turn.

Island

Aether Spellbomb

{U}, Sacrifice Aether Spellbomb: Return target creature to its owner's hand.
{1}, Sacrifice Aether Spellbomb: Draw a card.

Auriok Salvagers

{1}{W}: Return target artifact card with mana value 1 or less from your graveyard to your hand.

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Roar of Reclamation

Each player returns all artifact cards from their graveyard to the battlefield.

Arcbound Crusher

Trample
Whenever another artifact enters, put a +1/+1 counter on Arcbound Crusher.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Lumengrid Sentinel

Flying
Whenever an artifact you control enters, you may tap target permanent.

Vedalken Archmage

Whenever you cast an artifact spell, draw a card.

Arcbound Reclaimer

Remove a +1/+1 counter from Arcbound Reclaimer: Put target artifact card from your graveyard on top of your library.
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Myr Servitor

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