Roiling Vortex

At the beginning of each player's upkeep, Roiling Vortex deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, Roiling Vortex deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Guttural Response

Searing Blood

Searing Blood deals 2 damage to target creature. When that creature dies this turn, Searing Blood deals 3 damage to the creature's controller.

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.

Eidolon of the Great Revel

Whenever a player casts a spell with mana value 3 or less, Eidolon of the Great Revel deals 2 damage to that player.

Tormod's Crypt

{T}, Sacrifice Tormod's Crypt: Exile target player's graveyard.

Molten Rain

Destroy target land. If that land was nonbasic, Molten Rain deals 2 damage to the land's controller.

Goblin Guide

Haste
Whenever Goblin Guide attacks, defending player reveals the top card of their library. If it's a land card, that player puts it into their hand.

Mountain

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Sokenzan, Crucible of Defiance

{T}: Add {R}.
Channel — {3}{R}, Discard Sokenzan, Crucible of Defiance: Create two 1/1 colorless Spirit creature tokens. They gain haste until end of turn. This ability costs {1} less to activate for each legendary creature you control.

Skullcrack

Players can't gain life this turn. Damage can't be prevented this turn. Skullcrack deals 3 damage to target player or planeswalker.

Searing Blaze

Searing Blaze deals 1 damage to target player or planeswalker and 1 damage to target creature that player or that planeswalker's controller controls.
Landfall — If you had a land enter the battlefield under your control this turn, Searing Blaze deals 3 damage to that player or planeswalker and 3 damage to that creature instead.

Lightning Bolt

Lightning Bolt 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.)

Dragon's Claw

Whenever a player casts a red spell, you may gain 1 life.

Smash to Smithereens

Destroy target artifact. Smash to Smithereens deals 3 damage to that artifact's controller.

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)