Explore the Underdark

Search your library for up to two basic land cards and/or Gate cards, put them onto the battlefield tapped, then shuffle.
You take the initiative.

Birds of Paradise

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Have

Sandsteppe Citadel

Sandsteppe Citadel enters the battlefield tapped.
{T}: Add {W}, {B}, or {G}.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Island

Manor Gate

Manor Gate enters the battlefield tapped.
As Manor Gate enters the battlefield, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Maze's End

Maze's End enters the battlefield tapped.
{T}: Add {C}.
{3}, {T}, Return Maze's End to its owner's hand: Search your library for a Gate card, put it onto the battlefield, then shuffle. If you control ten or more Gates with different names, you win the game.

Exotic Orchard

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

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Archelos, Lagoon Mystic

As long as Archelos, Lagoon Mystic is tapped, other permanents enter the battlefield tapped.
As long as Archelos is untapped, other permanents enter the battlefield untapped.

Nomad Outpost

Nomad Outpost enters the battlefield tapped.
{T}: Add {R}, {W}, or {B}.

Gruul Guildgate

Gruul Guildgate enters the battlefield tapped.
{T}: Add {R} or {G}.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Citadel Gate

Citadel Gate enters the battlefield tapped.
As Citadel Gate enters the battlefield, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Black Dragon Gate

Black Dragon Gate enters the battlefield tapped.
As Black Dragon Gate enters the battlefield, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters the battlefield tapped unless you control two or more basic lands.

Unclaimed Territory

As Unclaimed Territory enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

Frontier Bivouac

Frontier Bivouac enters the battlefield tapped.
{T}: Add {G}, {U}, or {R}.

Dimir Guildgate

Dimir Guildgate enters the battlefield tapped.
{T}: Add {U} or {B}.

Fellwar Stone

Path of Ancestry

Path of Ancestry enters the battlefield tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Azorius Guildgate

Azorius Guildgate enters the battlefield tapped.
{T}: Add {W} or {U}.

Mystic Monastery

Mystic Monastery enters the battlefield tapped.
{T}: Add {U}, {R}, or {W}.

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Faeburrow Elder

Vigilance
Faeburrow Elder gets +1/+1 for each color among permanents you control.
{T}: For each color among permanents you control, add one mana of that color.

Gateway Plaza

Gateway Plaza enters the battlefield tapped.
When Gateway Plaza enters the battlefield, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.

Cinder Glade

({T}: Add {R} or {G}.)
Cinder Glade enters the battlefield tapped unless you control two or more basic lands.

Crumbling Necropolis

Crumbling Necropolis enters the battlefield tapped.
{T}: Add {U}, {B}, or {R}.

Sol Ring

Baldur's Gate

{T}: Add {C}.
{2}, {T}: Add X mana of any one color, where X is the number of other Gates you control.

Golgari Guildgate

Golgari Guildgate enters the battlefield tapped.
{T}: Add {B} or {G}.

Swamp

Gond Gate

Gates you control enter the battlefield untapped.
{T}: Add {C}.
{T}: Add one mana of any color that a Gate you control could produce.

Arcane Signet

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

Mountain

Forest

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Secluded Courtyard

As Secluded Courtyard enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

Selesnya Guildgate

Selesnya Guildgate enters the battlefield tapped.
{T}: Add {G} or {W}.

Simic Guildgate

Simic Guildgate enters the battlefield tapped.
{T}: Add {G} or {U}.

Savage Lands

Savage Lands enters the battlefield tapped.
{T}: Add {B}, {R}, or {G}.

Spelunking

When Spelunking enters the battlefield, draw a card, then you may put a land card from your hand onto the battlefield. If you put a Cave onto the battlefield this way, you gain 4 life.
Lands you control enter the battlefield untapped.

Open the Gates

Search your library for a basic land card or Gate card, reveal it, put it into your hand, then shuffle.

Plains

Boros Guildgate

Boros Guildgate enters the battlefield tapped.
{T}: Add {R} or {W}.

Izzet Guildgate

Izzet Guildgate enters the battlefield tapped.
{T}: Add {U} or {R}.

Cultivate

Cliffgate

Cliffgate enters the battlefield tapped.
As Cliffgate enters the battlefield, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Navigation Orb

{2}, {T}, Sacrifice Navigation Orb: Search your library for up to two basic land cards and/or Gate cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Command Tower

Alloy Myr

Jungle Shrine

Jungle Shrine enters the battlefield tapped.
{T}: Add {R}, {G}, or {W}.

Basilisk Gate

{T}: Add {C}.
{2}, {T}: Target creature gets +X/+X until end of turn, where X is the number of Gates you control. Activate only as a sorcery.

Plaza of Harmony

When Plaza of Harmony enters the battlefield, if you control two or more Gates, you gain 3 life.
{T}: Add {C}.
{T}: Add one mana of any type that a Gate you control could produce.

Sea Gate

Sea Gate enters the battlefield tapped.
As Sea Gate enters the battlefield, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Ornithopter of Paradise

Arcane Sanctum

Arcane Sanctum enters the battlefield tapped.
{T}: Add {W}, {U}, or {B}.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Orzhov Guildgate

Orzhov Guildgate enters the battlefield tapped.
{T}: Add {W} or {B}.

Circuitous Route

Search your library for up to two basic land cards and/or Gate cards, put them onto the battlefield tapped, then shuffle.

Skyshroud Claim

Search your library for up to two Forest cards, put them onto the battlefield, then shuffle.

Opulent Palace

Opulent Palace enters the battlefield tapped.
{T}: Add {B}, {G}, or {U}.

Darksteel Ingot

Indestructible (Effects that say "destroy" don't destroy this artifact.)
{T}: Add one mana of any color.