Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

Lumbering Falls

Lumbering Falls enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}: Lumbering Falls becomes a 3/3 green and blue Elemental creature with hexproof until end of turn. It's still a land.

Exotic Orchard

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

Plaxcaster Frogling

Graft 3 (This creature enters with three +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{2}: Target creature with a +1/+1 counter on it gains shroud until end of turn. (It can't be the target of spells or abilities.)

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Quandrix Campus

Quandrix Campus enters tapped.
{T}: Add {G} or {U}.
{4}, {T}: Scry 1.

Splinterfright

Trample
Splinterfright's power and toughness are each equal to the number of creature cards in your graveyard.
At the beginning of your upkeep, mill two cards.

Kasmina's Transmutation

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

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Teferi's Ageless Insight

If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Croaking Counterpart

Create a token that's a copy of target non-Frog creature, except it's a 1/1 green Frog.
Flashback {3}{G}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Omnibian

{T}: Target creature becomes a Frog with base power and toughness 3/3 until end of turn.

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Willow Geist

Trample
Whenever one or more cards leave your graveyard, put a +1/+1 counter on Willow Geist.
When Willow Geist dies, you gain life equal to its power.

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."

Forgotten Creation

Skulk (This creature can't be blocked by creatures with greater power.)
At the beginning of your upkeep, you may discard all the cards in your hand. If you do, draw that many cards.

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.)

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.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

Cephalid Vandal

At the beginning of your upkeep, put a shred counter on Cephalid Vandal. Then mill a card for each shred counter on Cephalid Vandal.

Froghemoth

Trample, haste
Whenever Froghemoth deals combat damage to a player, exile up to that many target cards from their graveyard. Put a +1/+1 counter on Froghemoth for each creature card exiled this way. You gain 1 life for each noncreature card exiled this way.

The Myriad Pools

(Transforms from The Everflowing Well.)
{T}: Add {U}.
Whenever you cast a permanent spell using mana produced by The Myriad Pools, up to one other target permanent you control becomes a copy of that spell until end of turn.

The Everflowing Well

When The Everflowing Well enters, mill two cards, then draw two cards.
Descend 8 — At the beginning of your upkeep, if there are eight or more permanent cards in your graveyard, transform The Everflowing Well.

The Everflowing Well // The Myriad Pools

Forest

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Traumatize

Target player mills half their library, rounded down.

Ertai's Familiar

Phasing (This phases in or out before you untap during each of your untap steps. While it's phased out, it's treated as though it doesn't exist.)
When Ertai's Familiar phases out or leaves the battlefield, mill three cards.
{U}: Until your next upkeep, Ertai's Familiar can't phase out.

Bear Umbra

Enchant creature
Enchanted creature gets +2/+2 and has "Whenever this creature attacks, untap all lands you control."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Genesis Wave

Reveal the top X cards of your library. You may put any number of permanent cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield into your graveyard.

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

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.)

Island

Cephalid Illusionist

Whenever Cephalid Illusionist becomes the target of a spell or ability, mill three cards.
{2}{U}, {T}: Prevent all combat damage that would be dealt to and dealt by target creature you control this turn.

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Thassa's Oracle

When Thassa's Oracle enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Rapid Hybridization

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

Golgari Grave-Troll

Golgari Grave-Troll enters with a +1/+1 counter on it for each creature card in your graveyard.
{1}, Remove a +1/+1 counter from Golgari Grave-Troll: Regenerate Golgari Grave-Troll.
Dredge 6 (If you would draw a card, you may mill six cards instead. If you do, return this card from your graveyard to your hand.)

Have

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

Command Tower

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

Grolnok, the Omnivore

Whenever a Frog you control attacks, mill three cards.
Whenever a permanent card is put into your graveyard from your library, exile it with a croak counter on it.
You may play lands and cast spells from among cards you own in exile with croak counters on them.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Fierce Empath

When this creature enters, you may search your library for a creature card with mana value 6 or greater, reveal it, put it into your hand, then shuffle.

Poison Dart Frog

Reach
{T}: Add one mana of any color.
{2}: Poison Dart Frog gains deathtouch until end of turn.

Crocanura

Reach (This creature can block creatures with flying.)
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Candlestick

Equipped creature gets +1/+1 and has "Whenever this creature attacks, surveil 2." (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{2}, Sacrifice Candlestick: Draw a card.
Equip {2}

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Temple of Mystery

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 {G} or {U}.

The Thirteenth Doctor

Paradox — Whenever you cast a spell from anywhere other than your hand, put a +1/+1 counter on target creature.
Team TARDIS — At the beginning of your end step, untap each creature you control with a counter on it.

Hermit Druid

{G}, {T}: Reveal cards from the top of your library until you reveal a basic land card. Put that card into your hand and all other cards revealed this way into your graveyard.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Crawling Sensation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more land cards are put into your graveyard from anywhere for the first time each turn, create a 1/1 green Insect creature token.

Hinterland Harbor

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

Frilled Mystic

Flash
When Frilled Mystic enters, you may counter target spell.

Tangled Islet

({T}: Add {G} or {U}.)
Tangled Islet enters tapped.

Mystic Snake

Flash
When Mystic Snake enters, counter target spell.

Sol Ring

Llanowar Elves

Counterspell

Jade Avenger

Bushido 2 (Whenever this creature blocks or becomes blocked, it gets +2/+2 until end of turn.)

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Fetch Quest

Mill seven cards. Then put a creature, enchantment, or land card from among the milled cards onto the battlefield.

Bramble Familiar

{T}: Add {G}.
{1}{G}, {T}, Discard a card: Return Bramble Familiar to its owner's hand.

Bramble Familiar // Fetch Quest

Crawling Infestation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more creature cards are put into your graveyard from anywhere during your turn, create a 1/1 green Insect creature token. This ability triggers only once each turn.

Thought Scour

Target player mills two cards.
Draw a card.

Perpetual Timepiece

{T}: Mill two cards.
{2}, Exile Perpetual Timepiece: Shuffle any number of target cards from your graveyard into your library.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Spore Frog

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

Druidic Ritual

You may mill three cards. Then return up to one creature card and up to one land card from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Court of Cunning

When Court of Cunning enters, you become the monarch.
At the beginning of your upkeep, any number of target players each mill two cards. If you're the monarch, each of those players mills ten cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Folio of Fancies

Players have no maximum hand size.
{X}{X}, {T}: Each player draws X cards.
{2}{U}, {T}: Each opponent mills cards equal to the number of cards in their hand.

Arcane Signet

Mental Note

Deranged Assistant

Excavating Anurid

When Excavating Anurid enters, you may sacrifice a land. If you do, draw a card.
Threshold — As long as seven or more cards are in your graveyard, Excavating Anurid gets +1/+1 and has vigilance.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.