Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Guttersnipe

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

Flame Blitz

At the beginning of your end step, Flame Blitz deals 5 damage to each planeswalker.
Cycling {2} ({2}, Discard this card: Draw a card.)

Flamebreak

Flamebreak deals 3 damage to each creature without flying and each player. Creatures dealt damage this way can't be regenerated this turn.

Skewer the Critics

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Skewer the Critics deals 3 damage to any target.

Rift Bolt

Rift Bolt deals 3 damage to any target.
Suspend 1—{R} (Rather than cast this card from your hand, you may pay {R} and exile it with a time counter 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.)

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Blasphemous Act

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

Landslide

Sacrifice any number of Mountains. Landslide deals that much damage to target player or planeswalker.

Worldfire

Exile all permanents. Exile all cards from all hands and graveyards. Each player's life total becomes 1.

Browbeat

Any player may have Browbeat deal 5 damage to them. If no one does, target player draws three cards.

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Elixir of Immortality

{2}, {T}: You gain 5 life. Shuffle Elixir of Immortality and your graveyard into their owner's library.

Mountain

Breaking Point

Any player may have Breaking Point deal 6 damage to them. If no one does, destroy all creatures. Creatures destroyed this way can't be regenerated.

Chain Lightning

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay {R}{R}. If the player does, they may copy this spell and may choose a new target for that copy.

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.)

Exquisite Firecraft

Exquisite Firecraft deals 4 damage to any target.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, this spell can't be countered.

Vexing Devil

When Vexing Devil enters, any opponent may have it deal 4 damage to them. If a player does, sacrifice Vexing Devil.