Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Aetherize

Return all attacking creatures to their owner's hand.

Secret Identity

Choose one —
• Conceal — Until end of turn, target creature you control becomes a Citizen with base power and toughness 1/1 and gains hexproof.
• Reveal — Until end of turn, target creature you control becomes a Hero with base power and toughness 3/4 and gains flying and vigilance.

Arcane Signet

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

Soporific Springs

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

Sink into Stupor

Return target spell or nonland permanent an opponent controls to its owner's hand.

Sink into Stupor // Soporific Springs

Loran's Escape

Target artifact or creature gains hexproof and indestructible until end of turn. Scry 1.

Counterspell

Staggering Insight

Enchant creature
Enchanted creature gets +1/+1 and has lifelink and "Whenever this creature deals combat damage to a player, draw a card."

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Plains

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Mask of Memory

Whenever equipped creature deals combat damage to a player, you may draw two cards. If you do, discard a card.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

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}.)

Farewell

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

Sea of Clouds

This land enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Lightning Greaves

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

Wraith, Vicious Vigilante

Double strike
Fear Gas — Wraith can't be blocked.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Island

Fellwar Stone

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

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

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.")

Cid, Timeless Artificer

Artifact creatures and Heroes you control get +1/+1 for each Artificer you control and each Artificer card in your graveyard.
A deck can have any number of cards named Cid, Timeless Artificer.
Cycling {W}{U} ({W}{U}, Discard this card: Draw a card.)

Sol Ring

Spectacular Spider-Man

Flash
{1}: Spectacular Spider-Man gains flying until end of turn.
{1}, Sacrifice Spectacular Spider-Man: Creatures you control gain hexproof and indestructible until end of turn.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Flawless Maneuver

If you control a commander, you may cast this spell without paying its mana cost.
Creatures you control gain indestructible until end of turn.

Curiosity

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

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Hallowed Fountain

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

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Spider-Sense

Web-slinging {U} (You may cast this spell for {U} if you also return a tapped creature you control to its owner's hand.)
Counter target instant spell, sorcery spell, or triggered ability.

Surge of Salvation

You and permanents you control gain hexproof until end of turn. Prevent all damage that black and/or red sources would deal to creatures you control this turn.

Talisman of Progress

{T}: Add {C}.
{T}: Add {W} or {U}. This artifact deals 1 damage to you.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

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.