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.

Sword of Light and Shadow

Equipped creature gets +2/+2 and has protection from white and from black.
Whenever equipped creature deals combat damage to a player, you gain 3 life and you may return up to one target creature card from your graveyard to your hand.
Equip {2}

Umezawa's Jitte

Whenever equipped creature deals combat damage, put two charge counters on Umezawa's Jitte.
Remove a charge counter from Umezawa's Jitte: Choose one —
• Equipped creature gets +2/+2 until end of turn.
• Target creature gets -1/-1 until end of turn.
• You gain 2 life.
Equip {2}

Mox Opal

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

Ancestral Recall

Island

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Voltaic Key

Cloudpost

Cloudpost enters tapped.
{T}: Add {C} for each Locus on the battlefield.

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Crucible of Worlds

Master Transmuter

{U}, {T}, Return an artifact you control to its owner's hand: You may put an artifact card from your hand onto the battlefield.

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.

Blightsteel Colossus

Trample, infect, indestructible
If Blightsteel Colossus would be put into a graveyard from anywhere, reveal Blightsteel Colossus and shuffle it into its owner's library instead.

Etched Champion

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

Seat of the Synod

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Ornithopter

Engineered Explosives

Sunburst (This enters with a charge counter on it for each color of mana spent to cast it.)
{2}, Sacrifice Engineered Explosives: Destroy each nonland permanent with mana value equal to the number of charge counters on Engineered Explosives.

Time Vault

Time Vault enters tapped.
Time Vault doesn't untap during your untap step.
If you would begin your turn while Time Vault is tapped, you may skip that turn instead. If you do, untap Time Vault.
{T}: Take an extra turn after this one.

Sol Ring

Glimmerpost

When Glimmerpost enters, you gain 1 life for each Locus on the battlefield.
{T}: Add {C}.