Lair of the Hydra

If you control two or more other lands, this land enters tapped.
{T}: Add {G}.
{X}{G}: Until end of turn, this land becomes an X/X green Hydra creature. It's still a land. X can't be 0.

Strict Proctor

Flying
Whenever a permanent entering causes a triggered ability to trigger, counter that ability unless its controller pays {2}.

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Treasure Vault

{T}: Add {C}.
{X}{X}, {T}, Sacrifice this land: Create X Treasure tokens.

Mutavault

{T}: Add {C}.
{1}: This land becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Hidden Strings

You may tap or untap target permanent, then you may tap or untap another target permanent.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

The Book of Exalted Deeds

At the beginning of your end step, if you gained 3 or more life this turn, create a 3/3 white Angel creature token with flying.
{W}{W}{W}, {T}, Exile The Book of Exalted Deeds: Put an enlightened counter on target Angel. It gains "You can't lose the game and your opponents can't win the game." Activate only as a sorcery.

Steel Seraph

Prototype {1}{W}{W} — 3/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Flying
At the beginning of combat on your turn, target creature you control gains your choice of flying, vigilance, or lifelink until end of turn.

Spara's Headquarters

({T}: Add {G}, {W}, or {U}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Hallowed Fountain

({T}: Add {W} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Mirran Safehouse

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

Castle Ardenvale

This land enters tapped unless you control a Plains.
{T}: Add {W}.
{2}{W}{W}, {T}: Create a 1/1 white Human creature token.

Lotus Field

Hexproof
This land enters tapped.
When this land enters, sacrifice two lands.
{T}: Add three mana of any one color.

Teferi, Hero of Dominaria

+1: Draw a card. At the beginning of the next end step, untap up to two lands.
−3: Put target nonland permanent into its owner's library third from the top.
−8: You get an emblem with "Whenever you draw a card, exile target permanent an opponent controls."

Discontinuity

During your turn, this spell costs {2}{U}{U} less to cast.
End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Urza's Sylex

{2}{W}{W}, {T}, Exile Urza's Sylex: Each player chooses six lands they control. Destroy all other permanents. Activate only as a sorcery.
When Urza's Sylex is put into exile from the battlefield, you may pay {2}. If you do, search your library for a planeswalker card, reveal it, put it into your hand, then shuffle.

Haywire Mite

When this creature dies, you gain 2 life.
{G}, Sacrifice this creature: Exile target noncreature artifact or noncreature enchantment.

Farewell

Choose one or more —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all graveyards.

Sylvan Scrying

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

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

The Filigree Sylex

{T}: Put an oil counter on The Filigree Sylex.
{T}, Sacrifice The Filigree Sylex: Destroy each nonland permanent with mana value equal to the number of oil counters on The Filigree Sylex.
{T}, Remove ten oil counters from among permanents you control and sacrifice The Filigree Sylex: It deals 10 damage to any target.

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Boseiju, Who Endures

{T}: Add {G}.
Channel — {1}{G}, Discard this card: Destroy target artifact, enchantment, or nonbasic land an opponent controls. That player may search their library for a land card with a basic land type, put it onto the battlefield, then shuffle. This ability costs {1} less to activate for each legendary creature you control.

Pithing Needle

As this artifact enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

Memory Deluge

Look at the top X cards of your library, where X is the amount of mana spent to cast this spell. Put two of them into your hand and the rest on the bottom of your library in a random order.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tormod's Crypt

{T}, Sacrifice this artifact: Exile target player's graveyard.

Cityscape Leveler

Trample
When you cast this spell and whenever this creature attacks, destroy up to one target nonland permanent. Its controller creates a tapped Powerstone token.
Unearth {8}

Sunfall

Exile all creatures. Incubate X, where X is the number of creatures exiled this way. (Create an Incubator token with X +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)

Portable Hole

When this artifact enters, exile target nonland permanent an opponent controls with mana value 2 or less until this artifact leaves the battlefield.

Plains

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard this card: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Golos, Tireless Pilgrim

When Golos enters, you may search your library for a land card, put that card onto the battlefield tapped, then shuffle.
{2}{W}{U}{B}{R}{G}: Exile the top three cards of your library. You may play them this turn without paying their mana costs.

Temple Garden

({T}: Add {G} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Dragonlord Dromoka

This spell can't be countered.
Flying, lifelink
Your opponents can't cast spells during your turn.

Thespian's Stage

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

The Stone Brain

{2}, {T}, Exile The Stone Brain: Choose a card name. Search target opponent's graveyard, hand, and library for up to four cards with that name and exile them. That player shuffles, then draws a card for each card exiled from their hand this way. Activate only as a sorcery.

Vizier of Tumbling Sands

{T}: Untap another target permanent.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle this card, untap target permanent.

Karn, the Great Creator

Activated abilities of artifacts your opponents control can't be activated.
+1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.
−2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

Restorative Burst

Return up to two target creature, land, and/or planeswalker cards from your graveyard to your hand. Each player gains 4 life. Exile Restorative Burst.

Pestilent Cauldron

{T}, Discard a card: Create a 1/1 black and green Pest creature token with "When this token dies, you gain 1 life."
{1}, {T}: Each opponent mills cards equal to the amount of life you gained this turn.
{4}, {T}: Exile four target cards from a single graveyard. Draw a card.