Krark, the Thumbless

Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)

Fellwar Stone

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

Scalding Tarn

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

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}.

Steam Vents

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

Storm-Kiln Artist

Storm-Kiln Artist gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

Reliquary Tower

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

Krark's Thumb

If you would flip a coin, instead flip two coins and ignore one.

Pyromancer Ascension

Whenever you cast an instant or sorcery spell that has the same name as a card in your graveyard, you may put a quest counter on Pyromancer Ascension.
Whenever you cast an instant or sorcery spell while Pyromancer Ascension has two or more quest counters on it, you may copy that spell. You may choose new targets for the copy.

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. Shivan Reef deals 1 damage to you.

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Izzet Charm

Choose one —
• Counter target noncreature spell unless its controller pays {2}.
• Izzet Charm deals 2 damage to target creature.
• Draw two cards, then discard two cards.

Mountain

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.

Quasiduplicate

Create a token that's a copy of target creature you control.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Rhystic Study

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

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Lithoform Engine

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Command Tower

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

Island

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Thousand-Year Storm

Whenever you cast an instant or sorcery spell, copy it for each other instant and sorcery spell you've cast before it this turn. You may choose new targets for the copies.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Veyran, Voice of Duality

Magecraft — Whenever you cast or copy an instant or sorcery spell, Veyran, Voice of Duality gets +1/+1 until end of turn.
If you casting or copying an instant or sorcery spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Mana Geyser

Add {R} for each tapped land your opponents control.

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

Swarm Intelligence

Whenever you cast an instant or sorcery spell, you may copy that spell. You may choose new targets for the copy.

Estrid's Invocation

You may have Estrid's Invocation enter as a copy of an enchantment you control, except it has "At the beginning of your upkeep, you may exile this enchantment. If you do, return it to the battlefield under its owner's control."

Lavaglide Pathway

Riverglide Pathway

Riverglide Pathway // Lavaglide Pathway

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, Electrostatic Field deals 1 damage to each opponent.

Gitaxian Probe

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

Dragon's Approach

Dragon's Approach deals 3 damage to each opponent. You may exile Dragon's Approach and four cards named Dragon's Approach from your graveyard. If you do, search your library for a Dragon creature card, put it onto the battlefield, then shuffle.
A deck can have any number of cards named Dragon's Approach.

Izzet Signet

Sakashima of a Thousand Faces

You may have Sakashima of a Thousand Faces enter as a copy of another creature you control, except it has Sakashima of a Thousand Faces's other abilities.
The "legend rule" doesn't apply to permanents you control.
Partner (You can have two commanders if both have partner.)

Thought Vessel

Sakashima the Impostor

You may have Sakashima the Impostor enter as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return this creature to its owner's hand at the beginning of the next end step."

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.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

Sol Ring

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Arcane Signet

Frantic Search

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

Past in Flames

Each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Fevered Visions

At the beginning of each player's end step, that player draws a card. If the player is your opponent and has four or more cards in hand, Fevered Visions deals 2 damage to that player.

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

Expedite

Target creature gains haste until end of turn.
Draw a card.

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.