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.

Bloodsworn Steward

Flying
Commander creatures you control get +2/+2 and have haste.

Fighting Chance

For each blocking creature, flip a coin. If you win the flip, prevent all combat damage that would be dealt by that creature this turn.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your 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.)

Reliquary Tower

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

Sol Ring

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

Okaun, Eye of Chaos

Partner with Zndrsplt, Eye of Wisdom (When this creature enters, target player may put Zndrsplt into their hand from their library, then shuffle.)
At the beginning of combat on your turn, flip a coin until you lose a flip.
Whenever a player wins a coin flip, double Okaun's power and toughness until end of turn.

Long-Term Plans

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

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Lightning Greaves

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

Negate

Aetherize

Return all attacking creatures to their owner's hand.

Fabricate

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

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

Frenetic Efreet

Flying
{0}: Flip a coin. If you win the flip, Frenetic Efreet phases out. If you lose the flip, sacrifice Frenetic Efreet. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

Zndrsplt, Eye of Wisdom

Partner with Okaun, Eye of Chaos (When this creature enters, target player may put Okaun into their hand from their library, then shuffle.)
At the beginning of combat on your turn, flip a coin until you lose a flip.
Whenever a player wins a coin flip, draw a card.

Mana Clash

You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.

Sorcerer's Strongbox

{2}, {T}: Flip a coin. If you win the flip, sacrifice Sorcerer's Strongbox and draw three cards.

Tribute Mage

When Tribute Mage enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Fiery Gambit

Flip a coin until you lose a flip or choose to stop flipping. If you lose a flip, Fiery Gambit has no effect. If you win one or more flips, Fiery Gambit deals 3 damage to target creature. If you win two or more flips, Fiery Gambit deals 6 damage to each opponent. If you win three or more flips, draw nine cards and untap all lands you control.

Relentless Assault

Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase.

Game of Chaos

Flip a coin. If you win the flip, you gain 1 life and target opponent loses 1 life, and you decide whether to flip again. If you lose the flip, you lose 1 life and that opponent gains 1 life, and that player decides whether to flip again. Double the life stakes with each flip.

Wizard Class

(Gain the next level as a sorcery to add its ability.)
You have no maximum hand size.
{2}{U}: Level 2
When this Class becomes level 2, draw two cards.
{4}{U}: Level 3
Whenever you draw a card, put a +1/+1 counter on target creature you control.

Proft's Eidetic Memory

When Proft's Eidetic Memory enters, draw a card.
You have no maximum hand size.
At the beginning of combat on your turn, if you've drawn more than one card this turn, put X +1/+1 counters on target creature you control, where X is the number of cards you've drawn this turn minus one.

Prisoner's Dilemma

Each opponent secretly chooses silence or snitch, then the choices are revealed. If each opponent chose silence, Prisoner's Dilemma deals 4 damage to each of them. If each opponent chose snitch, Prisoner's Dilemma deals 8 damage to each of them. Otherwise, Prisoner's Dilemma deals 12 damage to each opponent who chose silence.
Flashback {5}{R}{R}

Ponder

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

Squee's Revenge

Choose a number. Flip a coin that many times or until you lose a flip, whichever comes first. If you win all the flips, draw two cards for each flip.

Thundering Falls

({T}: Add {U} or {R}.)
Thundering Falls enters tapped.
When Thundering Falls enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Psychosis Crawler

Psychosis Crawler's power and toughness are each equal to the number of cards in your hand.
Whenever you draw a card, each opponent loses 1 life.

Tavern Scoundrel

Whenever you win a coin flip, create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")
{1}, {T}, Sacrifice another permanent: Flip a coin.

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.

Seize the Day

Untap target creature. After this main phase, there is an additional combat phase followed by an additional main phase.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Triskaidekaphile

You have no maximum hand size.
At the beginning of your upkeep, if you have exactly thirteen cards in your hand, you win the game.
{3}{U}: Draw a card.

Yusri, Fortune's Flame

Flying
Whenever Yusri, Fortune's Flame attacks, choose a number between 1 and 5. Flip that many coins. For each flip you win, draw a card. For each flip you lose, Yusri deals 2 damage to you. If you won five flips this way, you may cast spells from your hand this turn without paying their mana costs.

Arcane Signet

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

Zndrsplt's Judgment

For each player, choose friend or foe. Each friend creates a token that's a copy of a creature they control. Each foe returns a creature they control to its owner's hand.

The Locust God

Flying
Whenever you draw a card, create a 1/1 blue and red Insect creature token with flying and haste.
{2}{U}{R}: Draw a card, then discard a card.
When The Locust God dies, return it to its owner's hand at the beginning of the next end step.

Crooked Scales

{4}, {T}: Flip a coin. If you win the flip, destroy target creature an opponent controls. If you lose the flip, destroy target creature you control unless you pay {3} and repeat this process.

Spellbook

Roaming Throne

Ward {2}
As Roaming Throne enters, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Crazed Firecat

When Crazed Firecat enters, flip a coin until you lose a flip. Put a +1/+1 counter on Crazed Firecat for each flip you won.

Boompile

{T}: Flip a coin. If you win the flip, destroy all nonland permanents.

Mirror March

Whenever a nontoken creature you control enters, flip a coin until you lose a flip. For each flip you won, create a token that's a copy of that creature. Those tokens gain haste. Exile them at the beginning of the next end step.

Tide of War

Whenever one or more creatures block, flip a coin. If you win the flip, each blocking creature is sacrificed by its controller. If you lose the flip, each blocked creature is sacrificed by its controller.

Laboratory Maniac

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

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.)

Stitch in Time

Flip a coin. If you win the flip, take an extra turn after this one.

Planar Chaos

At the beginning of your upkeep, flip a coin. If you lose the flip, sacrifice Planar Chaos.
Whenever a player casts a spell, that player flips a coin. If they lose the flip, counter that spell.

Krark's Thumb

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

Mogg Assassin

{T}: You choose target creature an opponent controls, and that opponent chooses target creature. Flip a coin. If you win the flip, destroy the creature you chose. If you lose the flip, destroy the creature your opponent chose.

Chance Encounter

Whenever you win a coin flip, put a luck counter on Chance Encounter.
At the beginning of your upkeep, if Chance Encounter has ten or more luck counters on it, you win the game.

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.

Goblin Engineer

When Goblin Engineer enters, you may search your library for an artifact card, put it into your graveyard, then shuffle.
{R}, {T}, Sacrifice an artifact: Return target artifact card with mana value 3 or less from your graveyard to the battlefield.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Mutalith Vortex Beast

Trample
Warp Vortex — When Mutalith Vortex Beast enters, flip a coin for each opponent you have. For each flip you win, draw a card. For each flip you lose, Mutalith Vortex Beast deals 3 damage to that player.

Kazuul's Cliffs

Kazuul's Cliffs enters tapped.
{T}: Add {R}.

Kazuul's Fury

As an additional cost to cast this spell, sacrifice a creature.
Kazuul's Fury deals damage equal to the sacrificed creature's power to any target.

Kazuul's Fury // Kazuul's Cliffs

Ral Zarek

+1: Tap target permanent, then untap another target permanent.
−2: Ral Zarek deals 3 damage to any target.
−7: Flip five coins. Take an extra turn after this one for each coin that comes up heads.

Restless Spire

Restless Spire enters tapped.
{T}: Add {U} or {R}.
{U}{R}: Until end of turn, Restless Spire becomes a 2/1 blue and red Elemental creature with "During your turn, this creature has first strike." It's still a land.
Whenever Restless Spire attacks, scry 1.

Thought Vessel

Creepy Doll

Indestructible
Whenever Creepy Doll deals combat damage to a creature, flip a coin. If you win the flip, destroy that creature.

Island

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Mountain

Counterspell

Brainstorm

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

Desperate Gambit

Choose a source you control and flip a coin. If you win the flip, the next time that source would deal damage this turn, it deals double that damage instead. If you lose the flip, the next time it would deal damage this turn, prevent that damage.

Chaotic Goo

Chaotic Goo enters with three +1/+1 counters on it.
At the beginning of your upkeep, you may flip a coin. If you win the flip, put a +1/+1 counter on Chaotic Goo. If you lose the flip, remove a +1/+1 counter from Chaotic Goo.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Wirefly Hive

{3}, {T}: Flip a coin. If you win the flip, create a 2/2 colorless Insect artifact creature token with flying named Wirefly. If you lose the flip, destroy all permanents named Wirefly.

Footfall Crater

Enchant land
Enchanted land has "{T}: Target creature gains trample and haste until end of turn."
Cycling {1} ({1}, Discard this card: Draw a card.)