Voltaic Key

Emrakul, the Aeons Torn

This spell can't be countered.
When you cast this spell, take an extra turn after this one.
Flying, protection from spells that are one or more colors, annihilator 6
When Emrakul, the Aeons Torn is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Crystal Vein

{T}: Add {C}.
{T}, Sacrifice Crystal Vein: Add {C}{C}.

Mox Opal

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

Basalt Monolith

Basalt Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap Basalt Monolith.

Mystic Forge

You may look at the top card of your library any time.
You may cast artifact spells and colorless spells from the top of your library.
{T}, Pay 1 life: Exile the top card of your library.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Lotus Petal

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

Inventors' Fair

At the beginning of your upkeep, if you control three or more artifacts, you gain 1 life.
{T}: Add {C}.
{4}, {T}, Sacrifice Inventors' Fair: Search your library for an artifact card, reveal it, put it into your hand, then shuffle. Activate only if you control three or more artifacts.

Leyline of the Void

If Leyline of the Void is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

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.

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Karn, the Great Creator

Activated abilities of artifacts your opponents control can't be activated.
+1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.
−2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

Grim Monolith

Grim Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{4}: Untap Grim Monolith.