Koth of the Hammer

+1: Untap target Mountain. It becomes a 4/4 red Elemental creature until end of turn. It's still a land.
−2: Add {R} for each Mountain you control.
−5: You get an emblem with "Mountains you control have '{T}: This land deals 1 damage to any target.'"

Sarkhan, Dragonsoul

+2: Sarkhan, Dragonsoul deals 1 damage to each opponent and each creature your opponents control.
−3: Sarkhan, Dragonsoul deals 4 damage to target player or planeswalker.
−9: Search your library for any number of Dragon creature cards, put them onto the battlefield, then shuffle.

Pitchburn Devils

When Pitchburn Devils dies, it deals 3 damage to any target.

Blastfire Bolt

Blastfire Bolt deals 5 damage to target creature. Destroy all Equipment attached to that creature.

Avatar of Fury

If an opponent controls seven or more lands, this spell costs {6} less to cast.
Flying
{R}: Avatar of Fury gets +1/+0 until end of turn.

Heartfire

As an additional cost to cast this spell, sacrifice a creature or planeswalker.
Heartfire deals 4 damage to any target.

Gang of Devils

When Gang of Devils dies, it deals 3 damage divided as you choose among one, two, or three targets.

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.

Geyser Glider

Landfall — Whenever a land enters the battlefield under your control, Geyser Glider gains flying until end of turn.

Hellrider

Haste
Whenever a creature you control attacks, Hellrider deals 1 damage to the player or planeswalker it's attacking.

Structural Distortion

Exile target artifact or land. Structural Distortion deals 2 damage to that permanent's controller.

Havoc Devils

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Jaya's Immolating Inferno

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Jaya's Immolating Inferno deals X damage to each of up to three targets.

Blindblast

Blindblast deals 1 damage to target creature. That creature can't block this turn.
Draw a card.

Tunneling Geopede

Landfall — Whenever a land enters the battlefield under your control, Tunneling Geopede deals 1 damage to each opponent.

Jaya's Greeting

Jaya's Greeting deals 3 damage to target creature. Scry 1.

Sarkhan's Whelp

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever you activate an ability of a Sarkhan planeswalker, Sarkhan's Whelp deals 1 damage to any target.

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Akoum Hellkite

Flying
Landfall — Whenever a land enters the battlefield under your control, Akoum Hellkite deals 1 damage to any target. If that land is a Mountain, Akoum Hellkite deals 2 damage instead.

Hulking Devil

Sin Prodder

Menace
At the beginning of your upkeep, reveal the top card of your library. Any opponent may have you put that card into your graveyard. If a player does, Sin Prodder deals damage to that player equal to that card's mana value. Otherwise, put that card into your hand.

Vengeful Devil

Haste
Morbid — {T}: Vengeful Devil deals 1 damage to any target. Activate only if a creature died this turn.

Tibalt's Rager

When Tibalt's Rager dies, it deals 1 damage to any target.
{1}{R}: Tibalt's Rager gets +2/+0 until end of turn.

Bearer of the Heavens

When Bearer of the Heavens dies, destroy all permanents at the beginning of the next end step.

Oath of Chandra

When Oath of Chandra enters the battlefield, it deals 3 damage to target creature an opponent controls.
At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, Oath of Chandra deals 2 damage to each opponent.

Gibbering Fiend

When Gibbering Fiend enters the battlefield, it deals 1 damage to each opponent.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, Gibbering Fiend deals 1 damage to that player.

Impetuous Devils

Trample, haste
When Impetuous Devils attacks, up to one target creature defending player controls blocks it this combat if able.
At the beginning of the end step, sacrifice Impetuous Devils.

Charmbreaker Devils

At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Whenever you cast an instant or sorcery spell, Charmbreaker Devils gets +4/+0 until end of turn.

Mountain

Ratchet Bomb

{T}: Put a charge counter on Ratchet Bomb.
{T}, Sacrifice Ratchet Bomb: Destroy each nonland permanent with mana value equal to the number of charge counters on Ratchet Bomb.

Tibalt, Rakish Instigator

Your opponents can't gain life.
−2: Create a 1/1 red Devil creature token with "When this creature dies, it deals 1 damage to any target."

Chandra's Triumph

Chandra's Triumph deals 3 damage to target creature or planeswalker an opponent controls. Chandra's Triumph deals 5 damage instead if you control a Chandra planeswalker.

Jaya, Venerated Firemage

If another red source you control would deal damage to a permanent or player, it deals that much damage plus 1 to that permanent or player instead.
−2: Jaya, Venerated Firemage deals 2 damage to any target.

Chandra's Outrage

Chandra's Outrage deals 4 damage to target creature and 2 damage to that creature's controller.

Valakut Predator

Landfall — Whenever a land enters the battlefield under your control, Valakut Predator gets +2/+2 until end of turn.

Chandra, Fire Artisan

Whenever one or more loyalty counters are removed from Chandra, Fire Artisan, she deals that much damage to target opponent or planeswalker.
+1: Exile the top card of your library. You may play it this turn.
−7: Exile the top seven cards of your library. You may play them this turn.

Nesting Dragon

Flying
Landfall — Whenever a land enters the battlefield under your control, create a 0/2 red Dragon Egg creature token with defender and "When this creature dies, create a 2/2 red Dragon creature token with flying and '{R}: This creature gets +1/+0 until end of turn.'"

Nahiri's Wrath

As an additional cost to cast this spell, discard X cards.
Nahiri's Wrath deals damage equal to the total mana value of the discarded cards to each of up to X target creatures and/or planeswalkers.