Thundering Rebuke

Thundering Rebuke deals 4 damage to target creature or planeswalker.

Shock

Rodeo Pyromancers

Whenever you cast your first spell each turn, add {R}{R}.

Boltwave

Boltwave deals 3 damage to each opponent.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Kessig Flamebreather

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Agate Assault

Choose one —
• Agate Assault deals 4 damage to target creature. If that creature would die this turn, exile it instead.
• Exile target artifact.

Guttersnipe

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

Play with Fire

Play with Fire deals 2 damage to any target. If a player is dealt damage this way, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Thrill of Possibility

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

Erebor Flamesmith

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

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.)

Coruscation Mage

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Razorkin Needlehead

This creature has first strike during your turn.
Whenever an opponent draws a card, this creature deals 1 damage to them.

Red Dragon

Flying
Fire Breath — When this creature enters, it deals 4 damage to each opponent.

Mountain

Firebrand Archer

Fiery Annihilation

Fiery Annihilation deals 5 damage to target creature. Exile up to one target Equipment attached to that creature. If that creature would die this turn, exile it instead.

Call In a Professional

Players can't gain life this turn. Damage can't be prevented this turn. Call In a Professional deals 3 damage to any target. (Shield counters don't prevent this damage as they're removed.)

Hearthborn Battler

Haste
Whenever a player casts their second spell each turn, this creature deals 2 damage to target opponent.

Wrenn's Resolve

Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Goblin Negotiation

Goblin Negotiation deals X damage to target creature. Create a number of 1/1 red Goblin creature tokens equal to the amount of excess damage dealt to that creature this way.

Grab the Prize

As an additional cost to cast this spell, discard a card.
Draw two cards. If the discarded card wasn't a land card, Grab the Prize deals 2 damage to each opponent.

Unruly Catapult

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

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.