Ancient Den

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Forsaken Thresher

At the beginning of your first main phase, add one mana of any color.

Foreboding Statue

{T}: Add one mana of any color. Put an omen counter on this creature.
At the beginning of your end step, if there are three or more omen counters on this creature, untap it, then transform it.

Foreboding Statue // Forsaken Thresher

Power Depot

This land enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast artifact spells or activate abilities of artifacts.
Modular 1

Mystic Monastery

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

Training Center

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Clifftop Retreat

This land enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Spectator Seating

This land enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

Sea of Clouds

This land enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Sulfur Falls

This land enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Apex Observatory

This artifact enters tapped. As it enters, choose a card type shared among two exiled cards used to craft it.
{T}: The next spell you cast this turn of the chosen type can be cast without paying its mana cost.

Eye of Ojer Taq

{T}: Add one mana of any color.
Craft with two that share a card type {6} ({6}, Exile this artifact, Exile the two from among other permanents you control and/or cards from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Eye of Ojer Taq // Apex Observatory

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Raugrin Triome

({T}: Add {U}, {R}, or {W}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Deserted Beach

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Glacial Fortress

This land enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

The Golden-Gear Colossus

Vigilance, trample
Whenever The Golden-Gear Colossus enters or attacks, transform up to one other target double-faced artifact you control. Create two 1/1 colorless Gnome artifact creature tokens.

Tetzin, Gnome Champion

Whenever Tetzin or another double-faced artifact you control enters, mill three cards. You may put an artifact card from among them into your hand.
Craft with six artifacts {4} ({4}, Exile this artifact, Exile the six from among other permanents you control and/or cards from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Tetzin, Gnome Champion // The Golden-Gear Colossus

Seat of the Synod

Rustvale Bridge

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

Arcane Signet

Darksteel Citadel

Stormcarved Coast

This land enters tapped unless you control two or more other lands.
{T}: Add {U} or {R}.