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}

Smoldering Marsh

({T}: Add {B} or {R}.)
This land enters tapped unless you control two or more basic lands.

Tor Wauki the Younger

Reach, lifelink
If another source you control would deal noncombat damage to a permanent or player, it deals that much damage plus 1 to that permanent or player instead.
Whenever you cast an instant or sorcery spell, Tor Wauki deals 2 damage to any target.

Exsanguinate

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

Terminate

Destroy target creature. It can't be regenerated.

Scab-Clan Berserker

Haste
Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
Whenever an opponent casts a noncreature spell, if this creature is renowned, this creature deals 2 damage to that player.

Mountain

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Chandra's Incinerator

This spell costs {X} less to cast, where X is the total amount of noncombat damage dealt to your opponents this turn.
Trample
Whenever a source you control deals noncombat damage to an opponent, this creature deals that much damage to target creature or planeswalker that player controls.

Goblin Chainwhirler

First strike
When this creature enters, it deals 1 damage to each opponent and each creature and planeswalker they control.

Underworld Dreams

Whenever an opponent draws a card, this enchantment deals 1 damage to that player.

Browbeat

Any player may have Browbeat deal 5 damage to them. If no one does, target player draws three cards.

Blaze

Sign in Blood

Target player draws two cards and loses 2 life.

Shadowblood Ridge

Sol Ring

Brash Taunter

Indestructible
Whenever this creature is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: This creature fights another target creature.

Arcane Signet

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

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.

Blood Pact

Commander's Sphere

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

Lightning Reaver

Haste; fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever this creature deals combat damage to a player, put a charge counter on it.
At the beginning of your end step, this creature deals damage equal to the number of charge counters on it to each opponent.

Scytheclaw Raptor

Whenever a player casts a spell, if it's not their turn, this creature deals 4 damage to them.

Mana Geyser

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

Volcanic Fallout

This spell can't be countered.
Volcanic Fallout deals 2 damage to each creature and each player.

Swamp

Valakut Exploration

Landfall — Whenever a land you control enters, exile the top card of your library. You may play that card for as long as it remains exiled.
At the beginning of your end step, if there are cards exiled with this enchantment, put them into their owner's graveyard, then this enchantment deals that much damage to each opponent.

Zo-Zu the Punisher

Whenever a land enters, Zo-Zu deals 2 damage to that land's controller.

Clackbridge Troll

Trample, haste
When this creature enters, target opponent creates three 0/1 white Goat creature tokens.
At the beginning of combat on your turn, any opponent may sacrifice a creature of their choice. If a player does, tap this creature, you gain 3 life, and you draw a card.

Shock

Sulfuric Vortex

At the beginning of each player's upkeep, this enchantment deals 2 damage to that player.
If a player would gain life, that player gains no life 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.)

Lightning-Rig Crew

{T}: This creature deals 1 damage to each opponent.
Whenever you cast a Pirate spell, untap this creature.

Bedevil

Destroy target artifact, creature, or planeswalker.

Blisterspit Gremlin

{1}, {T}: This creature deals 1 damage to each opponent.
Whenever you cast a noncreature spell, untap this creature.

Rakdos Signet

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Shakedown Heavy

Menace
Whenever this creature attacks, defending player may have you draw a card. If they do, untap this creature and remove it from combat.

Theater of Horrors

At the beginning of your upkeep, exile the top card of your library.
During your turn, if an opponent lost life this turn, you may play lands and cast spells from among cards exiled with this enchantment.
{3}{R}: This enchantment deals 1 damage to target opponent or planeswalker.

Rakdos Charm

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

Pyromancer's Goggles

{T}: Add {R}. When that mana is spent to cast a red instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Command Tower

Sin Prodder

Menace
At the beginning of your upkeep, reveal the top card of your library. Any opponent may have you put that card into your graveyard. If a player does, this creature deals damage to that player equal to that card's mana value. Otherwise, put that card into your hand.

Syphon Soul

Syphon Soul deals 2 damage to each other player. You gain life equal to the damage dealt this way.

Unruly Catapult

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap this creature.

Into the Fire

Choose one —
• Into the Fire deals 2 damage to each creature, planeswalker, and battle.
• Put any number of cards from your hand on the bottom of your library, then draw that many cards plus one.

Temple of the False God

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

Shivan Gorge

{T}: Add {C}.
{2}{R}, {T}: Shivan Gorge deals 1 damage to each opponent.

Sizzle

Ribbons

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Each opponent loses X life.

Cut // Ribbons

Panicked Altisaur

Reach
{T}: This creature deals 2 damage to each opponent.

Foreboding Ruins

As this land enters, you may reveal a Swamp or Mountain card from your hand. If you don't, this land enters tapped.
{T}: Add {B} or {R}.

Dragonskull Summit

This land enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Rakdos Locket

{T}: Add {B} or {R}.
{B/R}{B/R}{B/R}{B/R}, {T}, Sacrifice this artifact: Draw two cards.

Magus of the Wheel

{1}{R}, {T}, Sacrifice this creature: Each player discards their hand, then draws seven cards.

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Forgotten Cave

This land enters tapped.
{T}: Add {R}.
Cycling {R} ({R}, Discard this card: Draw a card.)

Tunneling Geopede

Landfall — Whenever a land you control enters, this creature deals 1 damage to each opponent.

Rankle and Torbran

Flying, first strike, haste
Whenever Rankle and Torbran deals combat damage to a player or battle, choose any number —
• Each player creates a Treasure token.
• Each player sacrifices a creature of their choice.
• If a source would deal damage to a player or battle this turn, it deals that much damage plus 2 instead.

Slagstorm

Choose one —
• Slagstorm deals 3 damage to each creature.
• Slagstorm deals 3 damage to each player.

Spinerock Knoll

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
This land enters tapped.
{T}: Add {R}.
{R}, {T}: You may play the exiled card without paying its mana cost if an opponent was dealt 7 or more damage this turn.

Jaya's Immolating Inferno

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Jaya's Immolating Inferno deals X damage to each of up to three targets.

Temple of Malice

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {B} or {R}.

Fire Servant

If a red instant or sorcery spell you control would deal damage, it deals double that damage instead.

Blasphemous Act

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

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (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.)

Guttersnipe

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

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of each of your postcombat main phases, add {R} for each 1 life your opponents have lost this turn.

Breaking Point

Any player may have Breaking Point deal 6 damage to them. If no one does, destroy all creatures. Creatures destroyed this way can't be regenerated.

Ancient Craving

You draw three cards and you lose 3 life.

Maddening Hex

Enchant player
Whenever enchanted player casts a noncreature spell, roll a d6. This Aura deals damage to that player equal to the result. Then attach this Aura to another one of your opponents chosen at random.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Banefire

Banefire deals X damage to any target.
If X is 5 or more, this spell can't be countered and the damage can't be prevented.

Blightning

Blightning deals 3 damage to target player or planeswalker. That player or that planeswalker's controller discards two cards.

Breath of Malfegor

Breath of Malfegor deals 5 damage to each opponent.

Night's Whisper

Risk Factor

Target opponent may have Risk Factor deal 4 damage to them. If that player doesn't, you draw three cards.
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.)

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.