Electrickery

Electrickery deals 1 damage to target creature you don't control.
Overload {1}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Electrostatic Field

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

Earthquake

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

Flame Slash

Flame Slash deals 4 damage to target creature.

Blazing Volley

Blazing Volley deals 1 damage to each creature your opponents control.

Stonesplitter Bolt

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Stonesplitter Bolt deals X damage to target creature or planeswalker. If this spell was bargained, it deals twice X damage to that permanent instead.

Tectonic Hazard

Tectonic Hazard deals 1 damage to each opponent and each creature they control.

Invoke Calamity

You may cast up to two instant and/or sorcery spells with total mana value 6 or less from your graveyard and/or hand without paying their mana costs. If those spells would be put into your graveyard, exile them instead. Exile Invoke Calamity.

Fiendish Duo

First strike (This creature deals combat damage before creatures without first strike.)
If a source would deal damage to an opponent, it deals double that damage to that player instead.

Fire Servant

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

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.

Judith, Carnage Connoisseur

Whenever you cast an instant or sorcery spell, choose one —
• That spell gains deathtouch and lifelink.
• Create a 2/2 red Imp creature token with "When this creature dies, it deals 2 damage to each opponent."

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.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Return the Favor

Spree (Choose one or more additional costs.)
+ {1} — Copy target instant spell, sorcery spell, activated ability, or triggered ability. You may choose new targets for the copy.
+ {1} — Change the target of target spell or ability with a single target.

Star of Extinction

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

Recoup

Target sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (Mana cost includes color.)
Flashback {3}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Galvanize

Galvanize deals 3 damage to target creature. If you've drawn two or more cards this turn, Galvanize deals 5 damage to that creature instead.

Storm-Kiln Artist

Storm-Kiln Artist gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Lightning Greaves

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

Shivan Meteor

Shivan Meteor deals 13 damage to target creature.
Suspend 2—{1}{R}{R} (Rather than cast this card from your hand, you may pay {1}{R}{R} and exile it with two 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.)

Crush the Weak

Crush the Weak deals 2 damage to each creature. If a creature dealt damage this way would die this turn, exile it instead.
Foretell {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.)

End the Festivities

End the Festivities deals 1 damage to each opponent and each creature and planeswalker they control.

Imodane, the Pyrohammer

Whenever an instant or sorcery spell you control that targets only a single creature deals damage to that creature, Imodane deals that much damage to each opponent.