Chain Reaction

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

Howlpack Avenger

Whenever a permanent you control is dealt damage, Howlpack Avenger deals that much damage to any target.
{1}{R}: Howlpack Avenger gets +2/+0 until end of turn.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Ill-Tempered Loner

Whenever Ill-Tempered Loner is dealt damage, it deals that much damage to any target.
{1}{R}: Ill-Tempered Loner gets +2/+0 until end of turn.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Ill-Tempered Loner // Howlpack Avenger

Ashen Firebeast

{1}{R}: Ashen Firebeast deals 1 damage to each creature without flying.

Draconic Intervention

As an additional cost to cast this spell, exile an instant or sorcery card from your graveyard.
Draconic Intervention deals X damage to each non-Dragon creature, where X is the exiled card's mana value. If a creature dealt damage this way would die this turn, exile it instead.
Exile Draconic Intervention.

Magmaquake

Magmaquake deals X damage to each creature without flying and each planeswalker.

Structural Assault

Destroy all artifacts, then Structural Assault deals damage to each creature equal to the number of artifacts that were put into graveyards from the battlefield this turn.

Ill-Timed Explosion

Draw two cards. Then you may discard two cards. When you do, Ill-Timed Explosion deals X damage to each creature, where X is the greatest mana value among cards discarded this way.

Inferno

Inferno deals 6 damage to each creature and each player.

Mogg Maniac

Whenever Mogg Maniac is dealt damage, it deals that much damage to target opponent or planeswalker.

Crater Hellion

Echo {4}{R}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Crater Hellion enters the battlefield, it deals 4 damage to each other creature.

Chandra's Ignition

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

Savage Twister

Savage Twister deals X damage to each creature.

Battle of Frost and Fire

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Battle of Frost and Fire deals 4 damage to each non-Giant creature and each planeswalker.
II — Scry 3.
III — Whenever you cast a spell with mana value 5 or greater this turn, draw two cards, then discard a card.

Wrathful Red Dragon

Flying
Whenever a Dragon you control is dealt damage, it deals that much damage to any target that isn't a Dragon.

Cataclysmic Prospecting

Cataclysmic Prospecting deals X damage to each creature. For each mana from a Desert spent to cast this spell, create a tapped Treasure token.

Ryusei, the Falling Star

Flying
When Ryusei, the Falling Star dies, it deals 5 damage to each creature without flying.

Donna Noble

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)
Whenever Donna or a creature it's paired with is dealt damage, Donna deals that much damage to target opponent.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Subterranean Tremors

Subterranean Tremors deals X damage to each creature without flying. If X is 4 or more, destroy all artifacts. If X is 8 or more, create an 8/8 red Lizard creature token.

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, Chandra's Incinerator deals that much damage to target creature or planeswalker that player controls.

Swirling Sandstorm

Threshold — Swirling Sandstorm deals 5 damage to each creature without flying if seven or more cards are in your graveyard.

Linvala, Shield of Sea Gate

Flying
At the beginning of combat on your turn, if you have a full party, choose target nonland permanent an opponent controls. Until your next turn, it can't attack or block, and its activated abilities can't be activated.
Sacrifice Linvala: Choose hexproof or indestructible. Creatures you control gain that ability until end of turn.

Spiteful Banditry

When Spiteful Banditry enters the battlefield, it deals X damage to each creature.
Whenever one or more creatures your opponents control die, you create a Treasure token. This ability triggers only once each turn.

Molten Disaster

Kicker {R} (You may pay an additional {R} as you cast this spell.)
If this spell was kicked, it has split second. (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Molten Disaster deals X damage to each creature without flying and each player.

Sweltering Suns

Sweltering Suns deals 3 damage to each creature.
Cycling {3} ({3}, Discard this card: Draw a card.)

Soulfire Eruption

Choose any number of target creatures, planeswalkers, and/or players. For each of them, exile the top card of your library, then Soulfire Eruption deals damage equal to that card's mana value to that permanent or player. You may play the exiled cards until the end of your next turn.

Frontline Medic

Battalion — Whenever Frontline Medic and at least two other creatures attack, creatures you control gain indestructible until end of turn.
Sacrifice Frontline Medic: Counter target spell with {X} in its mana cost unless its controller pays {3}.

Wildfire

Each player sacrifices four lands. Wildfire deals 4 damage to each creature.

Brash Taunter

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

Burn Down the House

Choose one —
• Burn Down the House deals 5 damage to each creature and each planeswalker.
• Create three 1/1 red Devil creature tokens with "When this creature dies, it deals 1 damage to any target." They gain haste until end of turn.

Spitemare

Whenever Spitemare is dealt damage, it deals that much damage to any target.

Soul of New Phyrexia

Trample
{5}: Permanents you control gain indestructible until end of turn.
{5}, Exile Soul of New Phyrexia from your graveyard: Permanents you control gain indestructible until end of turn.

Boros Charm

Choose one —
• Boros Charm deals 4 damage to target player or planeswalker.
• Permanents you control gain indestructible until end of turn.
• Target creature gains double strike until end of turn.

Sorrow's Path

{T}: Choose two target blocking creatures an opponent controls. If each of those creatures could block all creatures that the other is blocking, remove both of them from combat. Each one then blocks all creatures the other was blocking.
Whenever Sorrow's Path becomes tapped, it deals 2 damage to you and each creature you control.

Firespout

Firespout deals 3 damage to each creature without flying if {R} was spent to cast this spell and 3 damage to each creature with flying if {G} was spent to cast this spell. (Do both if {R}{G} was spent.)

Lavabrink Floodgates

{T}: Add {R}{R}.
At the beginning of each player's upkeep, that player may put a doom counter on Lavabrink Floodgates or remove a doom counter from it. Then if it has three or more doom counters on it, sacrifice Lavabrink Floodgates. When you do, it deals 6 damage to each creature.

Fiery Confluence

Choose three. You may choose the same mode more than once.
• Fiery Confluence deals 1 damage to each creature.
• Fiery Confluence deals 2 damage to each opponent.
• Destroy target artifact.

Exocrine

Ravenous (This creature enters the battlefield with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Bio-plasmic Barrage — When Exocrine enters the battlefield, it deals X damage to each player and each other creature.

Nin, the Pain Artist

{X}{U}{R}, {T}: Nin, the Pain Artist deals X damage to target creature. That creature's controller draws X cards.

Incite Rebellion

For each player, Incite Rebellion deals damage to that player and each creature that player controls equal to the number of creatures they control.

Blazing Sunsteel

Equipped creature gets +1/+0 for each opponent you have.
Whenever equipped creature is dealt damage, it deals that much damage to any target.
Equip {4}

Deafening Clarion

Choose one or both —
• Deafening Clarion deals 3 damage to each creature.
• Creatures you control gain lifelink until end of turn.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Earth

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Earth deals X damage to each creature without flying.

Heaven

Heaven deals X damage to each creature with flying.

Heaven // Earth

Blasphemous Act

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

Megaton's Fate

Choose one —
• Disarm — Destroy target artifact. Create four Treasure tokens.
• Detonate — Megaton's Fate deals 8 damage to each creature. Each player gets four rad counters.

Delayed Blast Fireball

Delayed Blast Fireball deals 2 damage to each opponent and each creature they control. If this spell was cast from exile, it deals 5 damage to each opponent and each creature they control instead.
Foretell {4}{R}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Stuffy Doll

Indestructible
As Stuffy Doll enters the battlefield, choose a player.
Whenever Stuffy Doll is dealt damage, it deals that much damage to the chosen player.
{T}: Stuffy Doll deals 1 damage to itself.

Make a Stand

Creatures you control get +1/+0 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Flawless Maneuver

If you control a commander, you may cast this spell without paying its mana cost.
Creatures you control gain indestructible until end of turn.

Klauth's Will

Choose one. If you control a commander as you cast this spell, you may choose both.
• Breathe Flame — Klauth's Will deals X damage to each creature without flying.
• Smash Relics — Destroy up to X target artifacts and/or enchantments.

Star of Extinction

Destroy target land. Star of Extinction deals 20 damage to each creature and each planeswalker.

Avacyn, the Purifier

Flying
When this creature transforms into Avacyn, the Purifier, it deals 3 damage to each other creature and each opponent.

Archangel Avacyn

Flash
Flying, vigilance
When Archangel Avacyn enters the battlefield, creatures you control gain indestructible until end of turn.
When a non-Angel creature you control dies, transform Archangel Avacyn at the beginning of the next upkeep.

Archangel Avacyn // Avacyn, the Purifier

Scourge of Kher Ridges

Flying
{1}{R}: Scourge of Kher Ridges deals 2 damage to each creature without flying.
{5}{R}: Scourge of Kher Ridges deals 6 damage to each other creature with flying.

Incandescent Aria

Incandescent Aria deals 3 damage to each nontoken creature.

Anara, Wolvid Familiar

As long as it's your turn, commanders you control have indestructible. (Effects that say "destroy" don't destroy them. A creature with indestructible can't be destroyed by damage.)
Partner (You can have two commanders if both have partner.)

Anger of the Gods

Anger of the Gods deals 3 damage to each creature. If a creature dealt damage this way would die this turn, exile it instead.

Avacyn's Memorial

Indestructible
Other legendary permanents you control have indestructible.

Starstorm

Starstorm deals X damage to each creature.
Cycling {3} ({3}, Discard this card: Draw a card.)

Showstopping Surprise

Choose target creature you control. Turn it face up if it's face down. Then it deals damage equal to its power to each other creature.

Your Temple Is Under Attack

Choose one —
• Pray for Protection — Creatures you control gain indestructible until end of turn.
• Strike a Deal — You and target opponent each draw two cards.

Wrathful Raptors

Trample
Whenever a Dinosaur you control is dealt damage, it deals that much damage to any target that isn't a Dinosaur.

Boros Reckoner

Whenever Boros Reckoner is dealt damage, it deals that much damage to any target.
{R/W}: Boros Reckoner gains first strike until end of turn.

Radiant Flames

Converge — Radiant Flames deals X damage to each creature, where X is the number of colors of mana spent to cast this spell.

Surtland Frostpyre

Surtland Frostpyre enters the battlefield tapped.
{T}: Add {R}.
{2}{U}{U}{R}, {T}, Sacrifice Surtland Frostpyre: Scry 2. Surtland Frostpyre deals 2 damage to each creature. Activate only as a sorcery.

Coalhauler Swine

Whenever Coalhauler Swine is dealt damage, it deals that much damage to each player.

Destructive Force

Each player sacrifices five lands. Destructive Force deals 5 damage to each creature.

Metropolis Reformer

Flying, vigilance
You have hexproof.
Whenever Metropolis Reformer is dealt damage, you gain that much life.

Bastion Protector

Commander creatures you control get +2/+2 and have indestructible.

Hammerfist Giant

{T}: Hammerfist Giant deals 4 damage to each creature without flying and each player.

Jaya Ballard, Task Mage

{R}, {T}, Discard a card: Destroy target blue permanent.
{1}{R}, {T}, Discard a card: Jaya Ballard, Task Mage deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.
{5}{R}{R}, {T}, Discard a card: Jaya Ballard deals 6 damage to each creature and each player.

Song of Freyalise

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III — Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.

Bloodfire Colossus

{R}, Sacrifice Bloodfire Colossus: It deals 6 damage to each creature and each player.

Fire Tempest

Fire Tempest deals 6 damage to each creature and each player.

Spiteful Sliver

Sliver creatures you control have "Whenever this creature is dealt damage, it deals that much damage to target player or planeswalker."

Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Truefire Captain

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

Earthquake

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

Cave-In

You may exile a red card from your hand rather than pay this spell's mana cost.
Cave-In deals 2 damage to each creature and each player.

The Fourteenth Doctor

When you cast this spell, reveal the top fourteen cards of your library. Put all Doctor cards revealed this way into your graveyard and the rest on the bottom of your library in a random order.
You may have The Fourteenth Doctor enter the battlefield as a copy of a Doctor card in your graveyard that was put there from your library this turn. If you do, it gains haste until end of turn.

Storm's Wrath

Storm's Wrath deals 4 damage to each creature and each planeswalker.

Rolling Earthquake

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