Stoic Rebuttal

Metalcraft — This spell costs {1} less to cast if you control three or more artifacts.
Counter target spell.

Great Furnace

Shao Jun

Leap Strike — During your turn, Shao Jun has flying and first strike.
Rope Dart — Tap two untapped artifacts you control: Shao Jun deals 1 damage to each opponent.

Izzet Signet

Wandering Fumarole

This land enters tapped.
{T}: Add {U} or {R}.
{2}{U}{R}: Until end of turn, this land becomes a 1/4 blue and red Elemental creature with "{0}: Switch this creature's power and toughness until end of turn." It's still a land.

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.

Ongoing Investigation

Whenever one or more creatures you control deal combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
{1}{G}, Exile a creature card from your graveyard: Investigate. You gain 2 life.

Thopter Spy Network

At the beginning of your upkeep, if you control an artifact, create a 1/1 colorless Thopter artifact creature token with flying.
Whenever one or more artifact creatures you control deal combat damage to a player, draw a card.

Thoughtcast

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

Thopter Fabricator

Flying
Whenever you draw your second card each turn, create a 1/1 colorless Thopter artifact creature token with flying.
Crew 2

Sharding Sphinx

Flying
Whenever an artifact creature you control deals combat damage to a player, you may create a 1/1 blue Thopter artifact creature token with flying.

Thopter Engineer

When this creature enters, create a 1/1 colorless Thopter artifact creature token with flying.
Artifact creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Shrapnel Blast

As an additional cost to cast this spell, sacrifice an artifact.
Shrapnel Blast deals 5 damage to any target.

Mountain

Secluded Starforge

{T}: Add {C}.
{2}, {T}, Tap X untapped artifacts you control: Target creature gets +X/+0 until end of turn. Activate only as a sorcery.
{5}, {T}: Create a 2/2 colorless Robot artifact creature token.

Pia and Kiran Nalaar

When Pia and Kiran Nalaar enters, create two 1/1 colorless Thopter artifact creature tokens with flying.
{2}{R}, Sacrifice an artifact: Pia and Kiran Nalaar deals 2 damage to any target.

Silverbluff Bridge

This land enters tapped.
Indestructible
{T}: Add {U} or {R}.

Stridehangar Automaton

Thopters you control get +1/+1.
If one or more artifact tokens would be created under your control, those tokens plus an additional 1/1 colorless Thopter artifact creature token with flying are created instead.

Sunshot Militia

Tap two untapped artifacts and/or creatures you control: This creature deals 1 damage to each opponent. Activate only as a sorcery.

Ghirapur Aether Grid

Tap two untapped artifacts you control: This enchantment deals 1 damage to any target.

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. This land deals 1 damage to you.

Seat of the Synod

Galvanic Blast

Galvanic Blast deals 2 damage to any target.
Metalcraft — Galvanic Blast deals 4 damage instead if you control three or more artifacts.

Resonance Technician

Flying
When this creature enters, you may discard a card. If you do, investigate twice.
{T}, Tap X untapped artifacts you control: Copy target instant or sorcery spell you control with mana value X. You may choose new targets for the copy.

Island

Reverse Engineer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Draw three cards.

Thopter Mechanic

Whenever you draw your second card each turn, put a +1/+1 counter on this creature.
When this creature dies, create a 1/1 colorless Thopter artifact creature token with flying.