The Core

(Transforms from Matzalantli.)
Fathomless descent — {T}: Add X mana of any one color, where X is the number of permanent cards in your graveyard.

Matzalantli, the Great Door

{T}: Draw a card, then discard a card.
{4}, {T}: Transform Matzalantli, the Great Door. Activate only if there are four or more permanent types among cards in your graveyard. (Artifact, battle, creature, enchantment, land, and planeswalker are permanent types.)

Matzalantli, the Great Door // The Core

Krenko's Buzzcrusher

Flying, trample
When Krenko's Buzzcrusher enters, for each player, destroy up to one nonbasic land that player controls. For each land destroyed this way, its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.

Mirran Safehouse

As long as Mirran Safehouse is on the battlefield, it has all activated abilities of all land cards in all graveyards.

Kaslem's Strider

Kaslem's Stonetree

When Kaslem's Stonetree enters, look at the top six cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest on the bottom in a random order.
Craft with Cave {5}{G} ({5}{G}, Exile this artifact, Exile a Cave you control or a Cave card from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Kaslem's Stonetree // Kaslem's Strider

Demolition Field

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. That land's controller may search their library for a basic land card, put it onto the battlefield, then shuffle. You may search your library for a basic land card, put it onto the battlefield, then shuffle.

The Gitrog, Ravenous Ride

Trample, haste
Whenever The Gitrog, Ravenous Ride deals combat damage to a player, you may sacrifice a creature that saddled it this turn. If you do, draw X cards, then put up to X land cards from your hand onto the battlefield tapped, where X is the sacrificed creature's power.
Saddle 1

Jetsam

Each opponent mills three cards, then you may cast a spell from each opponent's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

Flotsam

Mill three cards. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Flotsam // Jetsam

Swamp

Forest

Echoing Deeps

You may have Echoing Deeps enter tapped as a copy of any land card in a graveyard, except it's a Cave in addition to its other types.
{T}: Add {C}.

Thalia and The Gitrog Monster

First strike, deathtouch
You may play an additional land on each of your turns.
Creatures and nonbasic lands your opponents control enter tapped.
Whenever Thalia and The Gitrog Monster attacks, sacrifice a creature or land, then draw a card.

Conduit Pylons

When Conduit Pylons enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Spelunking

When Spelunking enters, 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 untapped.

Wrenn and Realmbreaker

Lands you control have "{T}: Add one mana of any color."
+1: Up to one target land you control becomes a 3/3 Elemental creature with vigilance, hexproof, and haste until your next turn. It's still a land.
−2: Mill three cards. You may put a permanent card from among the milled cards into your hand.
−7: You get an emblem with "You may play lands and cast permanent spells from your graveyard."

Eccentric Farmer

When Eccentric Farmer enters, mill three cards, then you may return a land card from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Treasure Cove

(Transforms from Treasure Map.)
{T}: Add {C}.
{T}, Sacrifice a Treasure: Draw a card.

Treasure Map

{1}, {T}: Scry 1. Put a landmark counter on Treasure Map. Then if there are three or more landmark counters on it, remove those counters, transform Treasure Map, and create three Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Treasure Map // Treasure Cove

Nissa, Resurgent Animist

Landfall — Whenever a land you control enters, add one mana of any color. Then if this is the second time this ability has resolved this turn, reveal cards from the top of your library until you reveal an Elf or Elemental card. Put that card into your hand and the rest on the bottom of your library in a random order.

Hopeless Nightmare

When Hopeless Nightmare enters, each opponent discards a card and loses 2 life.
When Hopeless Nightmare is put into a graveyard from the battlefield, scry 2.
{2}{B}: Sacrifice Hopeless Nightmare.

Melek, Reforged Researcher

Melek, Reforged Researcher's power and toughness are each equal to twice the number of instant and sorcery cards in your graveyard.
The first instant or sorcery spell you cast each turn costs {3} less to cast.

Inscribed Tablet

{1}, {T}, Sacrifice Inscribed Tablet: Reveal the top five cards of your library. Put a land card from among them into your hand and the rest on the bottom of your library in a random order. If you didn't put a card into your hand this way, draw a card.

Boom Box

{6}, {T}, Sacrifice Boom Box: Destroy up to one target artifact, up to one target creature, and up to one target land.

Deadly Cover-Up

As an additional cost to cast this spell, you may collect evidence 6.
Destroy all creatures. If evidence was collected, exile a card from an opponent's graveyard. Then search its owner's graveyard, hand, and library for any number of cards with that name and exile them. That player shuffles, then draws a card for each card exiled from their hand this way.

Blanchwood Prowler

When Blanchwood Prowler enters, mill three cards. You may put a land card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Blanchwood Prowler. (To mill a card, put the top card of your library into your graveyard.)

Realmbreaker, the Invasion Tree

{2}, {T}: Target opponent mills three cards. Put a land card from their graveyard onto the battlefield tapped under your control. It gains "If this land would leave the battlefield, exile it instead of putting it anywhere else."
{10}, {T}, Sacrifice Realmbreaker, the Invasion Tree: Search your library for any number of Praetor cards, put them onto the battlefield, then shuffle.

Field of Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Field of Ruin: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

Arid Archway

Arid Archway enters tapped.
When Arid Archway enters, return a land you control to its owner's hand. If another Desert was returned this way, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}{C}.

Ray of Ruin

Exile target creature, Vehicle, or nonbasic land. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Volatile Fault

{T}: Add {C}.
{1}, {T}, Sacrifice Volatile Fault: Destroy target nonbasic land an opponent controls. That player may search their library for a basic land card, put it onto the battlefield, then shuffle. You create a Treasure token.

Blossoming Tortoise

Whenever Blossoming Tortoise enters or attacks, mill three cards, then return a land card from your graveyard to the battlefield tapped.
Activated abilities of lands you control cost {1} less to activate.
Land creatures you control get +1/+1.

Aftermath Analyst

When Aftermath Analyst enters, mill three cards.
{3}{G}, Sacrifice Aftermath Analyst: Return all land cards from your graveyard to the battlefield tapped.

The Fall of Kroog

Choose target opponent. Destroy target land that player controls. The Fall of Kroog deals 3 damage to that player and 1 damage to each creature they control.

Patient Naturalist

When Patient Naturalist enters, mill three cards. Put a land card from among the milled cards into your hand. If you can't, create a Treasure token. (To mill three cards, put the top three cards of your library into your graveyard.)

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.