Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Karakas

{T}: Add {W}.
{T}: Return target legendary creature to its owner's hand.

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.

Seat of the Synod

Frogmite

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

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Simulacrum Synthesizer

When Simulacrum Synthesizer enters, scry 2.
Whenever another artifact you control with mana value 3 or greater enters, create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."

Consulate Dreadnought

Crew 6 (Tap any number of creatures you control with total power 6 or more: This Vehicle becomes an artifact creature until end of turn.)

Memnite

Thoughtcast

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

Etherium Pteramander

Flying
Etherium Pteramander can block only creatures with flying.
{6}{B}: Adapt 4. This ability costs {1} less to activate for each other artifact you control. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)

Swamp

Island

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Surgical Extraction

({B/P} can be paid with either {B} or 2 life.)
Choose target card in a graveyard other than a basic land card. Search its owner's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.

Metallic Rebuke

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Counter target spell unless its controller pays {3}.

Refurbished Familiar

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Refurbished Familiar enters, each opponent discards a card. For each opponent who can't, you draw a card.

Disruptor Flute

Flash
As Disruptor Flute enters, choose a card name.
Spells with the chosen name cost {3} more to cast.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

Darksteel Citadel

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Thought Monitor

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Thought Monitor enters, draw two cards.

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

Ornithopter

Kappa Cannoneer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Ward {4}
Whenever Kappa Cannoneer or another artifact you control enters, put a +1/+1 counter on Kappa Cannoneer and it can't be blocked this turn.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)