Repercussion

Whenever a creature is dealt damage, Repercussion deals that much damage to that creature's controller.

Fire

Fire deals 2 damage divided as you choose among one or two targets.

Fire // Ice

Command Tower

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

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.

Shivan Gorge

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

Gelectrode

{T}: Gelectrode deals 1 damage to any target.
Whenever you cast an instant or sorcery spell, you may untap Gelectrode.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Goblin Fireslinger

{T}: Goblin Fireslinger deals 1 damage to target player or planeswalker.

Treasure Cruise

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

Basilisk Collar

Equipped creature has deathtouch and lifelink.
Equip {2}

The Locust God

Flying
Whenever you draw a card, create a 1/1 blue and red Insect creature token with flying and haste.
{2}{U}{R}: Draw a card, then discard a card.
When The Locust God dies, return it to its owner's hand at the beginning of the next end step.

Niv-Mizzet, Dracogenius

Flying
Whenever Niv-Mizzet, Dracogenius deals damage to a player, you may draw a card.
{U}{R}: Niv-Mizzet, Dracogenius deals 1 damage to any target.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Fear, Fire, Foes!

Damage can't be prevented this turn. Fear, Fire, Foes! deals X damage to target creature and 1 damage to each other creature with the same controller.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

Swiftfoot Boots

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

Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

Kessig Flamebreather

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

Sunshot Militia

Tap two untapped artifacts and/or creatures you control: Sunshot Militia deals 1 damage to each opponent. Activate only as a sorcery.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Third Path Iconoclast

Whenever you cast a noncreature spell, create a 1/1 colorless Soldier artifact creature token.

Mischievous Chimera

Flying
Whenever you cast your first spell during each opponent's turn, Mischievous Chimera deals 1 damage to each opponent. Scry 1.

Flame Jab

Flame Jab deals 1 damage to any target.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Immolation Shaman

Whenever an opponent activates an ability of an artifact, creature, or land that isn't a mana ability, Immolation Shaman deals 1 damage to that player.
{3}{R}{R}: Immolation Shaman gets +3/+3 and gains menace until end of turn.

Saheeli, Sublime Artificer

Whenever you cast a noncreature spell, create a 1/1 colorless Servo artifact creature token.
−2: Target artifact you control becomes a copy of another target artifact or creature you control until end of turn, except it's an artifact in addition to its other types.

Arcane Signet

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Izzet Signet

Expressive Iteration

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.

Tandem Lookout

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Tandem Lookout is paired with another creature, each of those creatures has "Whenever this creature deals damage to an opponent, draw a card."

Smash to Dust

Choose one —
• Destroy target artifact.
• Destroy target creature with defender.
• Smash to Dust deals 1 damage to each creature your opponents control.

Ghyrson Starn, Kelermorph

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Three Autostubs — Whenever another source you control deals exactly 1 damage to a permanent or player, Ghyrson Starn, Kelermorph deals 2 damage to that permanent or player.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Dual Shot

Dual Shot deals 1 damage to each of up to two target creatures.

Spikefield Cave

Spikefield Cave enters tapped.
{T}: Add {R}.

Spikefield Hazard

Spikefield Hazard deals 1 damage to any target. If a permanent dealt damage this way would die this turn, exile it instead.

Spikefield Hazard // Spikefield Cave

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.

Tectonic Hazard

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

Chandra's Spitfire

Flying
Whenever an opponent is dealt noncombat damage, Chandra's Spitfire gets +3/+0 until end of turn.

Thermo-Alchemist

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

Cascade Bluffs

{T}: Add {C}.
{U/R}, {T}: Add {U}{U}, {U}{R}, or {R}{R}.

Sunscorched Desert

When Sunscorched Desert enters, it deals 1 damage to target player or planeswalker.
{T}: Add {C}.

Erebor Flamesmith

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

Cast into the Fire

Choose one —
• Cast into the Fire deals 1 damage to each of up to two target creatures.
• Exile target artifact.

Preordain

Scry 2, then draw a card. (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.)

Strike It Rich

Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Unruly Catapult

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

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.")

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Serum Visions

End the Festivities

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

Lavaglide Pathway

Riverglide Pathway

Riverglide Pathway // Lavaglide Pathway

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Steam Clean

Return target nonland permanent to its owner's hand. (Then exile this card. You may cast the creature later from exile.)

Scalding Viper

Whenever an opponent casts a spell with mana value 3 or less, Scalding Viper deals 1 damage to that player.

Scalding Viper // Steam Clean

Detection Tower

{T}: Add {C}.
{1}, {T}: Until end of turn, your opponents and creatures your opponents control with hexproof can be the targets of spells and abilities you control as though they didn't have hexproof.

Firebrand Archer

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

Circle of Flame

Whenever a creature without flying attacks you or a planeswalker you control, Circle of Flame deals 1 damage to that creature.

Frostboil Snarl

As Frostboil Snarl enters, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters tapped.
{T}: Add {U} or {R}.

Ophidian Eye

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.