Stifle

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

Scion of Halaster

Commander creatures you own have "The first time you would draw a card each turn, instead look at the top two cards of your library. Put one of them into your graveyard and the other back on top of your library. Then draw a card."

Mnemonic Nexus

Each player shuffles their graveyard into their library.

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Arcane Signet

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

Halimar Depths

Halimar Depths enters tapped.
When Halimar Depths enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Turnabout

Choose artifact, creature, or land. Tap all untapped permanents of the chosen type target player controls, or untap all tapped permanents of that type that player controls.

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.)

An Offer You Can't Refuse

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

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Diplomatic Immunity

Enchant creature
Shroud (A permanent with shroud can't be the target of spells or abilities.)
Enchanted creature has shroud.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard Otawara, Soaring City: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Tunnel Vision

Choose a card name. Target player reveals cards from the top of their library until a card with that name is revealed. If it is, that player puts the rest of the revealed cards into their graveyard and puts the card with the chosen name on top of their library. Otherwise, the player shuffles.

Consider

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

Jeweled Lotus

{T}, Sacrifice Jeweled Lotus: Add three mana of any one color. Spend this mana only to cast your commander.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Dauthi Voidwalker

Shadow (This creature can block or be blocked by only creatures with shadow.)
If a card would be put into an opponent's graveyard from anywhere, instead exile it with a void counter on it.
{T}, Sacrifice Dauthi Voidwalker: Choose an exiled card an opponent owns with a void counter on it. You may play it this turn without paying its mana cost.

Leyline of the Void

If Leyline of the Void is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

Petrified Field

{T}: Add {C}.
{T}, Sacrifice Petrified Field: Return target land card from your graveyard to your hand.

Laboratory Maniac

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

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.

Reset

Cast this spell only during an opponent's turn after their upkeep step.
Untap all lands you control.

Long-Term Plans

Search your library for a card, then shuffle and put that card third from the top.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Mana Leak

Counter target spell unless its controller pays {3}.

Time Warp

Target player takes an extra turn after this one.

Mind's Desire

Shuffle your library. Then exile the top card of your library. Until end of turn, you may play that card without paying its mana cost.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Hindering Touch

Counter target spell unless its controller pays {2}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Frantic Search

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

Ray of Erasure

Target player mills a card.
Draw a card at the beginning of the next turn's upkeep.

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

Visions of Beyond

Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Circular Logic

Counter target spell unless its controller pays {1} for each card in your graveyard.
Madness {U} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Lim-Dûl's Vault

Look at the top five cards of your library. As many times as you choose, you may pay 1 life, put those cards on the bottom of your library in any order, then look at the top five cards of your library. Then shuffle and put the last cards you looked at this way on top in any order.

Doomsday

Search your library and graveyard for five cards and exile the rest. Put the chosen cards on top of your library in any order. You lose half your life, rounded up.

Ponder

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

Temporal Fissure

Return target permanent to its owner's hand.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Ad Nauseam

Reveal the top card of your library and put that card into your hand. You lose life equal to its mana value. You may repeat this process any number of times.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Snap

Return target creature to its owner's hand. Untap up to two lands.

Piracy

Until end of turn, you may tap lands you don't control for mana. Spend this mana only to cast spells.

Verdant Catacombs

{T}, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Reliquary Tower

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

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.)

Dig Through Time

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Sol Ring

High Tide

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

Takenuma, Abandoned Mire

{T}: Add {B}.
Channel — {3}{B}, Discard Takenuma, Abandoned Mire: Mill three cards, then return a creature or planeswalker card from your graveyard to your hand. This ability costs {1} less to activate for each legendary creature you control.

Brainstorm

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

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Tolarian Winds

Discard all the cards in your hand, then draw that many cards.

Vesuva

You may have Vesuva enter tapped as a copy of any land on the battlefield.

Brain Freeze

Target player mills three cards.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Gitaxian Probe

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

Lonely Sandbar

Lonely Sandbar enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

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.

Sapphire Medallion

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

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.

Traumatize

Target player mills half their library, rounded down.

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.)

Rewind

Counter target spell. Untap up to four lands.

Counterspell

Paradigm Shift

Exile all cards from your library. Then shuffle your graveyard into your library.

Mystic Remora

Cumulative upkeep {1} (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 opponent casts a noncreature spell, you may draw a card unless that player pays {4}.