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.

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, you may draw that many cards.

Deathcap Glade

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

Favor of the Overbeing

Enchant creature
As long as enchanted creature is green, it gets +1/+1 and has vigilance.
As long as enchanted creature is blue, it gets +1/+1 and has flying.

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Eternal Thirst

Enchant creature
Enchanted creature has lifelink and "Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature." (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Slip Out the Back

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Villainous Wealth

Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.

Golgari Rot Farm

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Arcane Flight

Enchant creature
Enchanted creature gets +1/+1 and has flying.

Simic Guildgate

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

Deprive

As an additional cost to cast this spell, return a land you control to its owner's hand.
Counter target spell.

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Way of the Thief

Enchant creature
Enchanted creature gets +2/+2.
Enchanted creature can't be blocked as long as you control a Gate.

Blessed Respite

Target player shuffles their graveyard into their library. Prevent all combat damage that would be dealt this turn.

Dimir Guildgate

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

Open the Gates

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

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Dreamroot Cascade

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

Rites of Flourishing

At the beginning of each player's draw step, that player draws an additional card.
Each player may play an additional land on each of their turns.

Sultai Charm

Choose one —
• Destroy target monocolored creature.
• Destroy target artifact or enchantment.
• Draw two cards, then discard a card.

Asceticism

Creatures you control have hexproof.
{1}{G}: Regenerate target creature. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Gond Gate

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

Tempt with Discovery

Tempting offer — Search your library for a land card and put it onto the battlefield. Each opponent may search their library for a land card and put it onto the battlefield. For each opponent who searches a library this way, search your library for a land card and put it onto the battlefield. Then each player who searched a library this way shuffles.

Explore

You may play an additional land this turn.
Draw a card.

Reliquary Tower

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

Watcher in the Web

Reach (This creature can block creatures with flying.)
This creature can block an additional seven creatures each combat.

Command Tower

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

Exotic Orchard

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

Broken Bond

Destroy target artifact or enchantment. You may put a land card from your hand onto the battlefield.

Sol Ring

Island

Mask of Griselbrand

Equipped creature has flying and lifelink.
Whenever equipped creature dies, you may pay X life, where X is its power. If you do, draw X cards.
Equip {3}

District Guide

When this creature enters, you may search your library for a basic land card or Gate card, reveal it, put it into your hand, then shuffle.

Druid Class

(Gain the next level as a sorcery to add its ability.)
Landfall — Whenever a land you control enters, you gain 1 life.
{2}{G}: Level 2
You may play an additional land on each of your turns.
{4}{G}: Level 3
When this Class becomes level 3, target land you control becomes a creature with haste and "This creature's power and toughness are each equal to the number of lands you control." It's still a land.

Urban Evolution

Draw three cards. You may play an additional land this turn.

Hydra's Growth

Enchant creature
When this Aura enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Decisive Denial

Choose one —
• Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
• Counter target noncreature spell unless its controller pays {3}.

Abundance

If you would draw a card, you may instead choose land or nonland and reveal cards from the top of your library until you reveal a card of the chosen kind. Put that card into your hand and put all other cards revealed this way on the bottom of your library in any order.

Golgari Guildgate

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

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Rampaging Baloths

Trample
Landfall — Whenever a land you control enters, create a 4/4 green Beast creature token.

Counterspell

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Swamp

Dimir Infiltrator

This creature can't be blocked.
Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Cranial Plating

Equipped creature gets +1/+0 for each artifact you control.
{B}{B}: Attach this Equipment to target creature you control.
Equip {1}

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Opulent Palace

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

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.

Thran Portal

This land enters tapped unless you control two or fewer other lands.
As this land enters, choose a basic land type.
This land is the chosen type in addition to its other types.
Mana abilities of this land cost an additional 1 life to activate.

Hinterland Harbor

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

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

Prevent all combat damage that would be dealt this turn.

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.

Mask of Riddles

Equipped creature has fear. (It can't be blocked except by artifact creatures and/or black creatures.)
Whenever equipped creature deals combat damage to a player, you may draw a card.
Equip {2}

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

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.

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 token: Add one mana of any color.")

Oona's Blackguard

Flying
Each other Rogue creature you control enters with an additional +1/+1 counter on it.
Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, that player discards a card.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Sea Gate

This land enters tapped.
As this land enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Black Dragon Gate

This land enters tapped.
As this land enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Gateway Plaza

This land enters tapped.
When this land enters, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.

Aetherize

Return all attacking creatures to their owner's hand.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: This land becomes a copy of target land, except it has this ability.

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Illusionist's Gambit

Cast this spell only during the declare blockers step on an opponent's turn.
Remove all attacking creatures from combat and untap them. After this phase, there is an additional combat phase. Each of those creatures attacks that combat if able. They can't attack you or planeswalkers you control that combat.

Navigation Orb

{2}, {T}, Sacrifice this artifact: 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.

Alpha Authority

Enchant creature
Enchanted creature has hexproof and can't be blocked by more than one creature.

Circuitous Route

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

Arcane Signet

Spore Frog

Sacrifice this creature: Prevent all combat damage that would be dealt this turn.

Decanter of Endless Water

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

Shipwreck Marsh

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

Forest

Ancestral Mask

Enchant creature
Enchanted creature gets +2/+2 for each other enchantment on the battlefield.

Krydle of Baldur's Gate

Whenever Krydle deals combat damage to a player, that player loses 1 life and mills a card, then you gain 1 life and scry 1.
Whenever you attack, you may pay {2}. If you do, target creature can't be blocked this turn.

Plaza of Harmony

When this land enters, 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.

Maze's End

This land enters tapped.
{T}: Add {C}.
{3}, {T}, Return this land 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.

Drowned Catacomb

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

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Growth Spiral

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

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Argentum Armor

Equipped creature gets +6/+6.
Whenever equipped creature attacks, destroy target permanent.
Equip {6}

Eureka Moment

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

Manor Gate

This land enters tapped.
As this land enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Woodland Cemetery

This land enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Guardian Augmenter

Flash
Commander creatures you control get +2/+2.
Commanders you control have hexproof.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Gatecreeper Vine

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