Spells and abilities your opponents control can't cause their controller to search their library.
-1: Target player mills four cards. Then exile each opponent's graveyard.
L:
5
{1}{U}{U}
Callaphe, Beloved of the Sea
Legendary Enchantment Creature - Demigod
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."
* /
3
--
Castle Vantress
Land
Castle Vantress enters the battlefield tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.
{U}{U}
Counterspell
Instant
Counter target spell.
{1}{B}{B}
Cry of the Carnarium
Sorcery
All creatures get -2/-2 until end of turn. Exile all creature cards in all graveyards that were put there from the battlefield this turn. If a creature would die this turn, exile it instead.
{2}{U}
Curse of the Bloody Tome
Enchantment - Aura Curse
Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.
{1}{B}{B}
Drown in Sorrow
Sorcery
All creatures get -2/-2 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)
{U}{B}
Drown in the Loch
Instant
Choose one --
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.
--
Drowned Catacomb
Land
Drowned Catacomb enters the battlefield tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.
{U}{B}
Duskmantle Guildmage
Creature - Human Wizard
{1}{U}{B}: Whenever a card is put into an opponent's graveyard from anywhere this turn, that player loses 1 life.
{2}{U}{B}: Target player mills two cards.
2 /
2
{1}{U}
Folio of Fancies
Artifact
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.
{2}{U}
Fraying Sanity
Enchantment - Aura Curse
Enchant player
At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.
{1}{U}
Frogify
Enchantment - Aura
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.)
{X}{U}{U}{U}
Gadwick, the Wizened
Legendary Creature - Human Wizard
When Gadwick, the Wizened enters the battlefield, draw X cards.
Whenever you cast a blue spell, tap target nonland permanent an opponent controls.
3 /
3
{U}{B}
Glimpse the Unthinkable
Sorcery
Target player mills ten cards.
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
{1}{U}{U}
Memory Erosion
Enchantment
Whenever an opponent casts a spell, that player mills two cards.
{U}{ // }{U}
Merfolk Secretkeeper // Venture Deeper
Creature - Merfolk Wizard // Sorcery - Adventure
Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)
0 /
4
{U}{U}
Merfolk Trickster
Creature - Merfolk Wizard
Flash
When Merfolk Trickster enters the battlefield, tap target creature an opponent controls. It loses all abilities until end of turn.
2 /
2
{1}{U}{B}
Mind Funeral
Sorcery
Target opponent reveals cards from the top of their library until four land cards are revealed. That player puts all cards revealed this way into their graveyard.
{X}{U}{B}
Mind Grind
Sorcery
Each opponent reveals cards from the top of their library until they reveal X land cards, then puts all cards revealed this way into their graveyard. X can't be 0.
{2}
Mindcrank
Artifact
Whenever an opponent loses life, that player mills that many cards. (Damage causes loss of life.)
{1}{U}
Negate
Instant
Counter target noncreature spell.
{2}{U}
Propaganda
Enchantment
Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.
{2}{U}
Psychic Corrosion
Enchantment
Whenever you draw a card, each opponent mills two cards.
{U}
Spell Pierce
Instant
Counter target noncreature spell unless its controller pays {2}.
{U}
Spell Snare
Instant
Counter target spell with mana value 2.
{2}{B}
Stab Wound
Enchantment - Aura
Enchant creature
Enchanted creature gets -2/-2.
At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.
{U}
Stream of Thought
Sorcery
Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
{U/B}{U/B}
Sygg, River Cutthroat
Legendary Creature - Merfolk Rogue
At the beginning of each end step, if an opponent lost 3 or more life this turn, you may draw a card. (Damage causes loss of life.)
1 /
3
{X}{U}{U}
Thassa's Intervention
Instant
Choose one --
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.
{1}{U}
Thassa's Rebuff
Instant
Counter target spell unless its controller pays {X}, where X is your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
{B}{B}{B}
Underworld Dreams
Enchantment
Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.
{1}{U}{B}
Vile Consumption
Enchantment
All creatures have "At the beginning of your upkeep, sacrifice this creature unless you pay 1 life."
{1}{U}
Wall of Lost Thoughts
Creature - Wall
Defender
When Wall of Lost Thoughts enters the battlefield, target player mills four cards.
0 /
4
--
Watery Grave
Land - Island Swamp
({T}: Add {U} or {B}.)
As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.
{1}{U}
Whirlpool Rider
Creature - Merfolk
When Whirlpool Rider enters the battlefield, shuffle the cards from your hand into your library, then draw that many cards.