Basalt Monolith

This artifact doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap this artifact.

Unwinding Clock

Untap all artifacts you control during each other player's untap step.

Tribute Mage

When this creature enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Seat of the Synod

Silver Myr

Leaden Myr

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.

Ancient Den

Darksteel Citadel

Vault of Whispers

Mistvault Bridge

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

Trinket Mage

When this creature enters, you may search your library for an artifact card with mana value 1 or less, reveal that card, put it into your hand, then shuffle.

Sol Ring

Razortide Bridge

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

Trophy Mage

When this creature enters, you may search your library for an artifact card with mana value 3, reveal it, put it into your hand, then shuffle.

Tawnos, Solemn Survivor

{2}, {T}: Create a token that's a copy of up to one target artifact token you control. Mill two cards.
{1}{W}{U}{B}, {T}, Sacrifice two artifact tokens, Exile an artifact or creature card from your graveyard: Create a token that's a copy of the exiled card, except it's an artifact in addition to its other types. Activate only as a sorcery.

Gold Myr

Slagstone Refinery

Whenever this artifact or another nontoken artifact you control is put into a graveyard from the battlefield or is put into exile from the battlefield, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Goldmire Bridge

This land enters tapped.
Indestructible
{T}: Add {W} or {B}.

Hall of Tagsin

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{4}, {T}: Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")