Myr Enforcer

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

Plains

Island

Razortide Bridge

Razortide Bridge enters the battlefield tapped.
Indestructible
{T}: Add {W} or {U}.

Seat of the Synod

Gearseeker Serpent

This spell costs {1} less to cast for each artifact you control.
{5}{U}: Gearseeker Serpent can't be blocked this turn.

Echoing Truth

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.

Steelfin Whale

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Whenever an artifact enters the battlefield under your control, untap Steelfin Whale.

Tormod's Crypt

{T}, Sacrifice Tormod's Crypt: Exile target player's graveyard.

Arcbound Mouser

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

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.)

Mightstone's Animation

Enchant artifact
When Mightstone's Animation enters the battlefield, draw a card.
Enchanted artifact is a creature with base power and toughness 4/4 in addition to its other types.

All That Glitters

Enchant creature
Enchanted creature gets +1/+1 for each artifact and/or enchantment you control.

Counterspell

Arcbound Prototype

Modular 2 (This creature enters the battlefield with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Cogworker's Puzzleknot

When Cogworker's Puzzleknot enters the battlefield, create a 1/1 colorless Servo artifact creature token.
{1}{W}, Sacrifice Cogworker's Puzzleknot: Create a 1/1 colorless Servo artifact creature token.

Bonesplitter

Chrome Courier

Flying
When Chrome Courier enters the battlefield, reveal the top two cards of your library. Put one of them into your hand and the other into your graveyard. If you put an artifact card into your hand this way, you gain 3 life.