Frantic Search

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

Reverse the Polarity

Choose one —
• Counter all other spells.
• Switch each creature's power and toughness until end of turn.
• Creatures can't be blocked this turn.

Candlekeep Sage

Commander creatures you own have "When this creature enters or leaves the battlefield, draw a card."

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Logic Knot

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Counter target spell unless its controller pays {X}.

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.

Cancel

Spell Rupture

Counter target spell unless its controller pays {X}, where X is the greatest power among creatures you control.

Negate

Essence Capture

Counter target creature spell. Put a +1/+1 counter on up to one target creature you control.

Teferi's Time Twist

Exile target permanent you control. Return that card to the battlefield under its owner's control at the beginning of the next end step. If it enters as a creature, it enters with an additional +1/+1 counter on it.

Bane's Contingency

Counter target spell. If that spell targets a commander you control, instead counter that spell, scry 2, then draw a card.

Reenact the Crime

Exile target nonland card in a graveyard that was put there from anywhere this turn. Copy it. You may cast the copy without paying its mana cost.

Blur

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

Disallow

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Hornswoggle

Counter target creature spell. You create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Displace

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.

Forbid

Buyback—Discard two cards. (You may discard two cards in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.)
Counter target spell.

Neutralize

Counter target spell.
Cycling {2} ({2}, Discard this card: Draw a card.)

Scourge of Fleets

When Scourge of Fleets enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Aetherspouts

For each attacking creature, its owner puts it on their choice of the top or bottom of their library.

Dispel

Wizards of Thay

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Instant and sorcery spells you cast cost {1} less to cast.
You may cast sorcery spells as though they had flash.

Disrupt

Counter target instant or sorcery spell unless its controller pays {1}.
Draw a card.

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Intervene

Counter target spell that targets a creature.

The Flood of Mars

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Water Always Wins — Whenever The Flood of Mars attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of The Flood of Mars. If it's a land, it becomes an Island in addition to its other types.

Flow of Ideas

Aquitect's Will

Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.

Rewind

Counter target spell. Untap up to four lands.

Forceful Denial

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Counter target spell.

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.

As Foretold

At the beginning of your upkeep, put a time counter on As Foretold.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on As Foretold.

Ertai's Scorn

This spell costs {U} less to cast if an opponent cast two or more spells this turn.
Counter target spell.

Spell Swindle

Counter target spell. Create X Treasure tokens, where X is that spell's mana value. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Turn Aside

Counter target spell that targets a permanent you control.

Charix, the Raging Isle

Spells your opponents cast that target Charix, the Raging Isle cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Golden Argosy

Whenever Golden Argosy attacks, exile each creature that crewed it this turn. Return them to the battlefield tapped under their owner's control at the beginning of the next end step.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Spell Syphon

Counter target spell unless its controller pays {1} for each blue permanent you control.

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Snowfall

Cumulative upkeep {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an Island is tapped for mana, its controller may add an additional {U}. If that Island is snow, its controller may add an additional {U}{U} instead. Spend this mana only to pay cumulative upkeep costs.

Dream Fracture

Counter target spell. Its controller draws a card.
Draw a card.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Power Sink

Counter target spell unless its controller pays {X}. If that player doesn't, they tap all lands with mana abilities they control and lose all unspent mana.

Condescend

Counter target spell unless its controller pays {X}. 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.)

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Harbinger of the Seas

Mana Leak

Counter target spell unless its controller pays {3}.

See Double

This spell can't be copied.
Choose one. If an opponent has eight or more cards in their graveyard, you may choose both instead.
• Copy target spell. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)
• Create a token that's a copy of target creature.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on Chasm Skulker.
When Chasm Skulker dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on Chasm Skulker. (They can't be blocked as long as defending player controls an Island.)