Gate Colossus

This spell costs {1} less to cast for each Gate you control.
Gate Colossus can't be blocked by creatures with power 2 or less.
Whenever a Gate enters the battlefield under your control, you may put Gate Colossus from your graveyard on top of your library.

Heap Gate

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{1}, {T}, Tap an untapped Gate you control: Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

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.

Sage of the Maze

{T}: Add two mana in any combination of colors.
{T}: Until end of turn, target land you control becomes an X/X Citizen creature with haste in addition to its other types, where X is twice the number of Gates you control. Activate only as a sorcery.
Tap an untapped Gate you control: Untap Sage of the Maze.

Simic Guildgate

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

Gatecreeper Vine

Defender
When Gatecreeper Vine enters the battlefield, you may search your library for a basic land card or a Gate card, reveal it, put it into your hand, then shuffle.

Sunhome, Fortress of the Legion

{T}: Add {C}.
{2}{R}{W}, {T}: Target creature gains double strike until end of turn.

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.

Guild Summit

When Guild Summit enters the battlefield, you may tap any number of untapped Gates you control. Draw a card for each Gate tapped this way.
Whenever a Gate enters the battlefield under your control, draw a card.

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.

Primeval Titan

Trample
Whenever Primeval Titan enters the battlefield or attacks, you may search your library for up to two land cards, put them onto the battlefield tapped, then shuffle.

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.

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.

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.

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.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Nine-Fingers Keene

Menace
Ward—Pay 9 life.
Whenever Nine-Fingers Keene deals combat damage to a player, look at the top nine cards of your library. You may put a Gate card from among them onto the battlefield. Then if you control nine or more Gates, put the rest into your hand. Otherwise, put the rest on the bottom of your library in a random order.

Golgari Guildgate

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

Gateway Sneak

Whenever a Gate enters the battlefield under your control, Gateway Sneak can't be blocked this turn.
Whenever Gateway Sneak deals combat damage to a player, draw a card.

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.

Gatebreaker Ram

Gatebreaker Ram gets +1/+1 for each Gate you control.
As long as you control two or more Gates, Gatebreaker Ram has vigilance and trample.

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.

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.

Circuitous Route

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

Dimir Guildgate

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

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.

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.