War Tax

{X}{U}: This turn, creatures can't attack unless their controller pays {X} for each attacking creature they control.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Frozen Aether

Artifacts, creatures, and lands your opponents control enter tapped.

Negate

Protean Thaumaturge

Constellation — Whenever an enchantment you control enters, you may have Protean Thaumaturge become a copy of another target creature, except it has this ability.

Energy Field

Prevent all damage that would be dealt to you by sources you don't control.
When a card is put into your graveyard from anywhere, sacrifice Energy Field.

Brine Giant

This spell costs {1} less to cast for each enchantment you control.

Nyx Lotus

Nyx Lotus enters tapped.
{T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Counterspell

Altar of the Pantheon

Your devotion to each color and each combination of colors is increased by one.
{T}: Add one mana of any color. If you control a God, a Demigod, or a legendary enchantment, you gain 1 life.

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.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Cartouche of Knowledge

Enchant creature you control
When Cartouche of Knowledge enters, draw a card.
Enchanted creature gets +1/+1 and has flying.

Web of Inertia

At the beginning of combat on each opponent's turn, that player may exile a card from their graveyard. If the player doesn't, creatures they control can't attack you this turn.

Thassa's Devourer

Constellation — Whenever Thassa's Devourer or another enchantment you control enters, target player mills two cards.

Steal Enchantment

Enchant enchantment
You control enchanted enchantment.

Public Enemy

Enchant creature
All creatures attack enchanted creature's controller each combat if able.
When enchanted creature dies, draw a card.

Counterbalance

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, counter that spell if it has the same mana value as the revealed card.

Copy Enchantment

You may have Copy Enchantment enter as a copy of any enchantment on the battlefield.

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Teferi's Realm

At the beginning of each player's upkeep, that player chooses artifact, creature, land, or non-Aura enchantment. All nontoken permanents of that type phase out. (While they're phased out, they're treated as though they don't exist. Each one phases in before its controller untaps during their next untap step.)

Living Breakthrough

Flying
Whenever you cast a spell, your opponents can't cast spells with the same mana value as that spell until your next turn.

Inventive Iteration

(As this Saga enters and after your draw step, add a lore counter.)
I — Return up to one target creature or planeswalker to its owner's hand.
II — Return an artifact card from your graveyard to your hand. If you can't, draw a card.
III — Exile this Saga, then return it to the battlefield transformed under your control.

Inventive Iteration // Living Breakthrough

Overburden

Whenever a player puts a nontoken creature onto the battlefield, that player returns a land they control to its owner's hand.

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Esior, Wardwing Familiar

Flying
Spells your opponents cast that target one or more commanders you control cost {3} more to cast.
Partner (You can have two commanders if both have partner.)

One with the Stars

Enchant creature or enchantment
Enchanted permanent is an enchantment and loses all other card types. (It still has its abilities, but it's no longer a creature.)

Spectral Adversary

Flash
Flying
When Spectral Adversary enters, you may pay {1}{U} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on Spectral Adversary, then up to that many other target artifacts, creatures, and/or enchantments phase out.

Aether Tunnel

Enchant creature
Enchanted creature gets +1/+0 and can't be blocked.

Aether Barrier

Whenever a player casts a creature spell, that player sacrifices a permanent of their choice unless they pay {1}.

Rootwater Shaman

You may cast Aura spells with enchant creature as though they had flash.

Whitewater Naiads

Constellation — Whenever Whitewater Naiads or another enchantment you control enters, target creature can't be blocked this turn.

Combat Research

Enchant creature
Enchanted creature has "Whenever this creature deals combat damage to a player, draw a card."
As long as enchanted creature is legendary, it gets +1/+1 and has ward {1}. (Whenever enchanted creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Monastery Siege

As Monastery Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your draw step, draw an additional card, then discard a card.
• Dragons — Spells your opponents cast that target you or a permanent you control cost {2} more to cast.

Shapeshifter's Marrow

At the beginning of each opponent's upkeep, that player reveals the top card of their library. If it's a creature card, the player puts the card into their graveyard and Shapeshifter's Marrow becomes a copy of that card. (If it does, it loses this ability.)

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Sage of Mysteries

Constellation — Whenever an enchantment you control enters, target player mills two cards.

Meletis Astronomer

Heroic — Whenever you cast a spell that targets Meletis Astronomer, look at the top three cards of your library. You may reveal an enchantment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Telepathy

Your opponents play with their hands revealed.

Eaten by Piranhas

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other colors, card types, and creature types.)

Archetype of Imagination

Creatures you control have flying.
Creatures your opponents control lose flying and can't have or gain flying.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Ever-Watching Threshold

Whenever an opponent attacks, if they attacked you and/or a planeswalker you control, draw a card.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Helm of the Gods

Equipped creature gets +1/+1 for each enchantment you control.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Mind Spring

Inertia Bubble

Enchant artifact
Enchanted artifact doesn't untap during its controller's untap step.

Island

Clever Impersonator

You may have Clever Impersonator enter as a copy of any nonland permanent on the battlefield.

Invisibility

Enchant creature
Enchanted creature can't be blocked except by Walls.

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Rayne, Academy Chancellor

Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, you may draw a card. You may draw an additional card if Rayne, Academy Chancellor is enchanted.

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Parallel Thoughts

When Parallel Thoughts enters, search your library for seven cards, exile them in a face-down pile, and shuffle that pile. Then shuffle your library.
If you would draw a card, you may instead put the top card of the pile you exiled into your hand.

Kasmina's Transmutation

Enchant creature
Enchanted creature loses all abilities and has base power and toughness 1/1.

Dissipation Field

Whenever a permanent deals damage to you, return it to its owner's hand.

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Confounding Conundrum

When Confounding Conundrum enters, draw a card.
Whenever a land enters under an opponent's control, if that player had another land enter the battlefield under their control this turn, they return a land they control to its owner's hand.

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.

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.)

Defiler of Dreams

Flying
As an additional cost to cast blue permanent spells, you may pay 2 life. Those spells cost {U} less to cast if you paid life this way. This effect reduces only the amount of blue mana you pay.
Whenever you cast a blue permanent spell, draw a card.

Psychic Surgery

Whenever an opponent shuffles their library, you may look at the top two cards of that library. You may exile one of those cards. Then put the rest on top of that library in any order.

Curator's Ward

Enchant permanent
Enchanted permanent has hexproof.
When enchanted permanent leaves the battlefield, if it was historic, draw two cards. (Artifacts, legendaries, and Sagas are historic.)

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Energy Flux

All artifacts have "At the beginning of your upkeep, sacrifice this artifact unless you pay {2}."

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Estrid's Invocation

You may have Estrid's Invocation enter as a copy of an enchantment you control, except it has "At the beginning of your upkeep, you may exile this enchantment. If you do, return it to the battlefield under its owner's control."

Propaganda

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

Sea Gate, Reborn

As Sea Gate, Reborn enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Sea Gate Restoration

Draw cards equal to the number of cards in your hand plus one. You have no maximum hand size for the rest of the game.

Sea Gate Restoration // Sea Gate, Reborn

Ravenform

Exile target artifact or creature. Its controller creates a 1/1 blue Bird creature token with flying.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

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.)

Soul Barrier

Whenever an opponent casts a creature spell, Soul Barrier deals 2 damage to that player unless they pay {2}.

Rogue's Passage

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

Callaphe, Beloved of the Sea

Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."

Saw It Coming

Counter target spell.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Copy Artifact

You may have Copy Artifact enter as a copy of any artifact on the battlefield, except it's an enchantment in addition to its other types.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Shoal Kraken

Constellation — Whenever an enchantment you control enters, you may draw a card. If you do, discard a card.

Mana Chains

Enchant creature
Enchanted creature has "Cumulative upkeep {1}." (At the beginning of its controller's upkeep, that player puts an age counter on it, then sacrifices it unless they pay its upkeep cost for each age counter on it.)