Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Arcane Signet

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

Roiling Vortex

At the beginning of each player's upkeep, Roiling Vortex deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, Roiling Vortex deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Scytheclaw Raptor

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

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Fiery Inscription

When Fiery Inscription enters the battlefield, the Ring tempts you.
Whenever you cast an instant or sorcery spell, Fiery Inscription deals 2 damage to each opponent.

Jeska's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Add {R} for each card in target opponent's hand.
• Exile the top three cards of your library. You may play them this turn.

Electrodominance

Electrodominance deals X damage to any target. You may cast a spell with mana value X or less from your hand without paying its mana cost.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Firebrand Archer

Whenever you cast a noncreature spell, Firebrand Archer deals 1 damage to each opponent.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters the battlefield, Rampaging Ferocidon deals 1 damage to that creature's controller.

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}

Lightning Greaves

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

Electrostatic Field

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

Sol Ring

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.

Harness the Storm

Whenever you cast an instant or sorcery spell from your hand, you may cast target card with the same name as that spell from your graveyard. (You still pay its costs.)

Embereth Blaze

Embereth Blaze deals 2 damage to any target. (Then exile this card. You may cast the enchantment later from exile.)

Virtue of Courage

Whenever a source you control deals noncombat damage to an opponent, you may exile that many cards from the top of your library. You may play those cards this turn.

Virtue of Courage // Embereth Blaze

Themberchaud

Trample
When Themberchaud enters the battlefield, he deals X damage to each other creature without flying and each player, where X is the number of Mountains you control.
You may exert Themberchaud as he attacks. When you do, he gains flying until end of turn. (An exerted creature won't untap during your next untap step.)

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Valakut, the Molten Pinnacle

Valakut, the Molten Pinnacle enters the battlefield tapped.
Whenever a Mountain enters the battlefield under your control, if you control at least five other Mountains, you may have Valakut, the Molten Pinnacle deal 3 damage to any target.
{T}: Add {R}.

Ruby Medallion

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

Locket of Yesterdays

Spells you cast cost {1} less to cast for each card with the same name as that spell in your graveyard.

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.)

Ramunap Ruins

{T}: Add {C}.
{T}, Pay 1 life: Add {R}.
{2}{R}{R}, {T}, Sacrifice a Desert: Ramunap Ruins deals 2 damage to each opponent.

Price of Progress

Price of Progress deals damage to each player equal to twice the number of nonbasic lands that player controls.

Guttersnipe

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

Mob Verdict

Secret council — Each player secretly votes for another player, then those votes are revealed. For each vote an opponent received, Mob Verdict deals 2 damage to that player and each creature that player controls. For each vote you received, draw a card.

Kessig Flamebreather

Whenever you cast a noncreature spell, Kessig Flamebreather deals 1 damage to each opponent.

Wheel of Misfortune

Each player secretly chooses a number 0 or greater, then all players reveal those numbers simultaneously and determine the highest and lowest numbers revealed this way. Wheel of Misfortune deals damage equal to the highest number to each player who chose that number. Each player who didn't choose the lowest number discards their hand, then draws seven cards.

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.

Zo-Zu the Punisher

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

Mountain

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

Drakuseth, Maw of Flames

Flying
Whenever Drakuseth, Maw of Flames attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Sulfuric Vortex

At the beginning of each player's upkeep, Sulfuric Vortex deals 2 damage to that player.
If a player would gain life, that player gains no life instead.

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Furnace of Rath

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

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your 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, Harsh Mentor deals 2 damage to that player.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Erebor Flamesmith

Whenever you cast an instant or sorcery spell, Erebor Flamesmith deals 1 damage to each opponent.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

The Great Work

(As this Saga enters and after your draw step, add a lore counter.)
I — The Great Work deals 3 damage to target opponent and each creature they control.
II — Create three Treasure tokens.
III — Until end of turn, you may cast instant and sorcery spells from any graveyard. If a spell cast this way would be put into a graveyard, exile it instead. Exile The Great Work, then return it to the battlefield (front face up).

Urabrask

First strike
Whenever you cast an instant or sorcery spell, Urabrask deals 1 damage to target opponent. Add {R}.
{R}: Exile Urabrask, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if you've cast three or more instant and/or sorcery spells this turn.

Urabrask // The Great Work

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.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Mind Stone

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

Solphim, Mayhem Dominus

If a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals double that damage to that player or permanent instead.
{1}{R/P}{R/P}, Discard two cards: Put an indestructible counter on Solphim, Mayhem Dominus. ({R/P} can be paid with either {R} or 2 life.)

Spellshock

Whenever a player casts a spell, Spellshock deals 2 damage to that player.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

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.

Mana Geyser

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

Blasphemous Act

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