Logan Feliciano

The sudden sinkhole was surprising enough, but nothing could have prepared you for the ancient city that was hidden underneath.

Swamp

A royal pain in the Fire Nation's backside.

The Duke, Rebel Sentry

The Duke enters with a +1/+1 counter on him.
{T}, Remove a counter from The Duke: Put a +1/+1 counter on another target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Earthbender Ascension

When this enchantment enters, earthbend 2. Then search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Landfall — Whenever a land you control enters, put a quest counter on this enchantment. When you do, if it has four or more quest counters on it, put a +1/+1 counter on target creature you control. It gains trample until end of turn.

Attacking

Find ways to always attack
(Theme color: {B})

Hidden Volcano

This land enters tapped.
{T}: Add {R}.
{4}{R}, {T}, Sacrifice this land: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

It devoured the shell's original owner long ago, but it's just about ready to start looking for a new home—and a meal to go with it.

Hermitic Nautilus

Vigilance
{1}{U}: This creature gets +3/-3 until end of turn.

The Komon Winaq left behind few written records, but their handiwork stands strong all throughout the Core.

Forgotten Monument

{T}: Add {C}.
Other Caves you control have "{T}, Pay 1 life: Add one mana of any color."

Mount Doom

{T}, Pay 1 life: Add {B} or {R}.
{1}{B}{R}, {T}: Mount Doom deals 1 damage to each opponent.
{5}{B}{R}, {T}, Sacrifice Mount Doom and a legendary artifact: Choose up to two creatures, then destroy the rest. Activate only as a sorcery.

Long List of the Ents

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after VI.)
I, II, III, IV, V, VI — Note a creature type that hasn't been noted for this Saga. When you next cast a creature spell of that type this turn, that creature enters with an additional +1/+1 counter on it.

Cavern of Souls

As this land enters, 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, and that spell can't be countered.

Pompeii

When you planeswalk to Pompeii and at the beginning of your upkeep, put an eruption counter on it.
Whenever you roll a blank on the planar die, scry 2. Then put an eruption counter on Pompeii.
When chaos ensues, Pompeii deals damage to each creature and each player equal to the number of eruption counters on Pompeii. Each player sacrifices a land of their choice. Then planeswalk.

"The woman twice dead, and her final message. He was drawn to this place of peace and solitude that he might divine her meaning."
—The Abbott

Mystic Monastery

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

"Love is a form of hope and, like hope, love abides in the face of everything."
—The Thirteenth Doctor

Carpet of Flowers

At the beginning of each of your main phases, if you haven't added mana with this ability this turn, you may add X mana of any one color, where X is the number of Islands target opponent controls.

"I must have made quite an impression."
—The Fourth Doctor

Canyon Slough

({T}: Add {B} or {R}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

"But stream and pool is wet and cool: so nice for feet! We only wish to catch a fish, so juicy-sweet!"
—Gollum

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Before the shadows of evening were long in happier lands, they went on again with only brief halts until they had come to the very midst of the Dead Marshes.

Smoldering Marsh

({T}: Add {B} or {R}.)
This land enters tapped unless you control two or more basic lands.

The keep was called the Hornburg, for a trumpet sounded upon the tower echoed in the Deep behind, as if armies long-forgotten were issuing to war from caves beneath the hills.

Shinka, the Bloodsoaked Keep

{T}: Add {R}.
{R}, {T}: Target legendary creature gains first strike until end of turn.

It emits a stinking cloud composed of millions of nascent microscopic organisms, each possessing a fragment of predatory sentience.

Toxicrene

Reach, deathtouch
Hypertoxic Miasma — All lands have "{T}: Add one mana of any color" and lose all other abilities.

Places of worship become frenzies of violence as the psychic call of the Hive Mind stirs Genestealer Cults to action.

Temple of Abandon

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {R} or {G}.

Primaris Eliminator

When this creature enters, choose one —
• Executioner Round — Destroy target creature.
• Hyperfrag Round — Creatures target player controls get -2/-2 until end of turn.

Opal Palace

{T}: Add {C}.
{1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game.

In the late stages of a Tyranid invasion, vast capillary towers funnel biomass to the Hive Ships waiting in orbit.

Command Tower

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