Havoc Festival

Players can't gain life.
At the beginning of each player's upkeep, that player loses half their life, rounded up.

Archaeomancer

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Counterspell

Curtains' Call

Undaunted (This spell costs {1} less to cast for each opponent.)
Destroy two target creatures.

Mindswipe

Counter target spell unless its controller pays {X}. Mindswipe deals X damage to that spell's controller.

Mercurial Chemister

{U}, {T}: Draw two cards.
{R}, {T}, Discard a card: This creature deals damage to target creature equal to the discarded card's mana value.

Crosis's Charm

Choose one —
• Return target permanent to its owner's hand.
• Destroy target nonblack creature. It can't be regenerated.
• Destroy target artifact.

Reliquary Tower

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

Rakdos's Return

Rakdos's Return deals X damage to target opponent or planeswalker. That player or that planeswalker's controller discards X cards.

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.")

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.")

Notion Thief

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.

Mystic Retrieval

Return target instant or sorcery card from your graveyard to your hand.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.

Diabolic Tutor

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

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle this card, all creatures get -2/-2 until end of turn.

Evacuation

Return all creatures to their owners' hands.

Essence Backlash

Counter target creature spell. Essence Backlash deals damage equal to that spell's power to its controller.

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Swamp

Steam Augury

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

Wild Ricochet

You may choose new targets for target instant or sorcery spell. Then copy that spell. You may choose new targets for the copy.

Epic Experiment

Exile the top X cards of your library. You may cast instant and sorcery spells with mana value X or less from among them without paying their mana costs. Then put all cards exiled this way that weren't cast into your graveyard.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Counterflux

This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Chasm Skulker

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

Vial Smasher the Fierce

Whenever you cast your first spell each turn, choose an opponent at random. Vial Smasher deals damage equal to that spell's mana value to that player or a planeswalker that player controls.
Partner (You can have two commanders if both have partner.)

Wild Evocation

At the beginning of each player's upkeep, that player reveals a card at random from their hand. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

Volcanic Vision

Return target instant or sorcery card from your graveyard to your hand. Volcanic Vision deals damage equal to that card's mana value to each creature your opponents control. Exile Volcanic Vision.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, this creature deals 2 damage to that player.

Mizzix of the Izmagnus

Whenever you cast an instant or sorcery spell with mana value greater than the number of experience counters you have, you get an experience counter.
Instant and sorcery spells you cast cost {1} less to cast for each experience counter you have.

Blatant Thievery

For each opponent, gain control of target permanent that player controls.

Charmbreaker Devils

At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Whenever you cast an instant or sorcery spell, this creature gets +4/+0 until end of turn.

Kraum, Ludevic's Opus

Flying, haste
Whenever an opponent casts their second spell each turn, draw a card.
Partner (You can have two commanders if both have partner.)

Kaervek the Merciless

Whenever an opponent casts a spell, Kaervek deals damage equal to that spell's mana value to any target.

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Mind's Dilation

Whenever an opponent casts their first spell each turn, that player exiles the top card of their library. If it's a nonland card, you may cast it without paying its mana cost.

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, this enchantment deals 2 damage to that player.

Command Tower

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

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.

Etherium-Horn Sorcerer

{1}{U}{R}: Return this creature to its owner's hand.
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.)

Rakdos Carnarium

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{R}.

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate this creature.

Island

Phthisis

Destroy target creature. Its controller loses life equal to its power plus its toughness.
Suspend 5—{1}{B} (Rather than cast this card from your hand, you may pay {1}{B} and exile it with five time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Evolving Wilds

Dreadbore

Ludevic, Necro-Alchemist

At the beginning of each player's end step, that player may draw a card if a player other than you lost life this turn.
Partner (You can have two commanders if both have partner.)

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Cruel Ultimatum

Target opponent sacrifices a creature of their choice, discards three cards, then loses 5 life. You return a creature card from your graveyard to your hand, draw three cards, then gain 5 life.

Inferno Titan

{R}: This creature gets +1/+0 until end of turn.
Whenever this creature enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Sol Ring

Rewind

Counter target spell. Untap up to four lands.

Jace's Sanctum

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

Prince of Thralls

Whenever a permanent an opponent controls is put into a graveyard, put that card onto the battlefield under your control unless that opponent pays 3 life.

Possibility Storm

Whenever a player casts a spell from their hand, that player exiles it, then exiles cards from the top of their library until they exile a card that shares a card type with it. That player may cast that card without paying its mana cost. Then they put all cards exiled with this enchantment on the bottom of their library in a random order.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Izzet Boilerworks

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{R}.

Dissipation Field

Whenever a permanent deals damage to you, return it to its owner's hand.

Cruel Entertainment

Choose target player and another target player. The first player controls the second player during the second player's next turn, and the second player controls the first player during the first player's next turn.

Treasure Cruise

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

Guttersnipe

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

Disallow

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

Dictate of the Twin Gods

Flash
If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Melek, Izzet Paragon

Play with the top card of your library revealed.
You may cast instant and sorcery spells from the top of your library.
Whenever you cast an instant or sorcery spell from your library, copy it. You may choose new targets for the copy.

Nicol Bolas, Planeswalker

+3: Destroy target noncreature permanent.
−2: Gain control of target creature.
−9: Nicol Bolas deals 7 damage to target player or planeswalker. That player or that planeswalker's controller discards seven cards, then sacrifices seven permanents of their choice.

Spelltwine

Exile target instant or sorcery card from your graveyard and target instant or sorcery card from an opponent's graveyard. Copy those cards. Cast the copies if able without paying their mana costs. Exile Spelltwine.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Mountain

Combustible Gearhulk

First strike
When this creature enters, target opponent may have you draw three cards. If the player doesn't, you mill three cards, then this creature deals damage to that player equal to the total mana value of those cards.

Fellwar Stone

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

Temporal Trespass

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Take an extra turn after this one. Exile Temporal Trespass.