Heartlash Cinder

Haste
Chroma — When Heartlash Cinder enters, it gets +X/+0 until end of turn, where X is the number of red mana symbols in the mana costs of permanents you control.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Mindsparker

First strike (This creature deals combat damage before creatures without first strike.)
Whenever an opponent casts a white or blue instant or sorcery spell, this creature deals 2 damage to that player.

Arc Runner

Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice Arc Runner.

Blistering Firecat

Trample, haste
At the beginning of the end step, sacrifice Blistering Firecat.
Morph {R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Lightning Mare

This spell can't be countered.
Lightning Mare can't be blocked by blue creatures.
{1}{R}: Lightning Mare gets +1/+0 until end of turn.

Electropotence

Whenever a creature you control enters, you may pay {2}{R}. If you do, that creature deals damage equal to its power to any target.

Soul's Fire

Target creature you control deals damage equal to its power to any target.

Heart-Piercer Manticore

When Heart-Piercer Manticore enters, you may sacrifice another creature. When you do, Heart-Piercer Manticore deals damage equal to that creature's power to any target.
Embalm {5}{R} ({5}{R}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Manticore with no mana cost. Embalm only as a sorcery.)

Flamekin Harbinger

When Flamekin Harbinger enters, you may search your library for an Elemental card, reveal it, then shuffle and put that card on top.

Thundermare

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermare enters, tap all other creatures.

Ball Lightning

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Noetic Scales

At the beginning of each player's upkeep, return to its owner's hand each creature that player controls with power greater than the number of cards in their hand.

Thud

As an additional cost to cast this spell, sacrifice a creature.
Thud deals damage equal to the sacrificed creature's power to any target.

Thunderblust

Haste
Thunderblust has trample as long as it has a -1/-1 counter on it.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Lightning Elemental

Haste (This creature can attack and {T} as soon as it comes under your control.)

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Nova Chaser

Trample
Champion an Elemental (When this enters, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Brighthearth Banneret

Elemental spells and Warrior spells you cast cost {1} less to cast.
Reinforce 1—{1}{R} ({1}{R}, Discard this card: Put a +1/+1 counter on target creature.)

Valakut Fireboar

Whenever Valakut Fireboar attacks, switch its power and toughness until end of turn.

Stigma Lasher

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever Stigma Lasher deals damage to a player, that player can't gain life for the rest of the game.

War Elemental

When War Elemental enters, sacrifice it unless an opponent was dealt damage this turn.
Whenever an opponent is dealt damage, put that many +1/+1 counters on War Elemental.

Sarkhan's Unsealing

Whenever you cast a creature spell with power 4, 5, or 6, Sarkhan's Unsealing deals 4 damage to any target.
Whenever you cast a creature spell with power 7 or greater, Sarkhan's Unsealing deals 4 damage to each opponent and each creature and planeswalker they control.

Hellspark Elemental

Trample, haste
At the beginning of the end step, sacrifice Hellspark Elemental.
Unearth {1}{R} ({1}{R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Charging Cinderhorn

Haste
At the beginning of each player's end step, if no creatures attacked this turn, put a fury counter on Charging Cinderhorn. Then Charging Cinderhorn deals damage equal to the number of fury counters on it to that player.

Magus of the Arena

{3}, {T}: Tap target creature you control and target creature of an opponent's choice they control. Those creatures fight each other. (Each deals damage equal to its power to the other.)

Sol Ring

Soulblast

As an additional cost to cast this spell, sacrifice all creatures you control.
Soulblast deals damage to any target equal to the total power of the sacrificed creatures.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Hell's Thunder

Flying, haste
At the beginning of the end step, sacrifice Hell's Thunder.
Unearth {4}{R} ({4}{R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Generator Servant

{T}, Sacrifice Generator Servant: Add {C}{C}. If that mana is spent on a creature spell, it gains haste until end of turn. (That creature can attack and {T} as soon as it comes under your control.)

Feldon of the Third Path

{2}{R}, {T}: Create a token that's a copy of target creature card in your graveyard, except it's an artifact in addition to its other types. It gains haste. Sacrifice it at the beginning of the next end step.

Skizzik

Kicker {R} (You may pay an additional {R} as you cast this spell.)
Trample, haste
At the beginning of the end step, if Skizzik wasn't kicked, sacrifice it.

Bloodshot Cyclops

{T}, Sacrifice a creature: Bloodshot Cyclops deals damage equal to the sacrificed creature's power to any target.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Valakut, the Molten Pinnacle

Valakut, the Molten Pinnacle enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have Valakut, the Molten Pinnacle deal 3 damage to any target.
{T}: Add {R}.

Rupture

Sacrifice a creature. Rupture deals damage equal to that creature's power to each creature without flying and each player.

Stalking Vengeance

Haste
Whenever another creature you control dies, it deals damage equal to its power to target player or planeswalker.

Arena

Crater Elemental

{R}, {T}, Sacrifice Crater Elemental: It deals 4 damage to target creature.
Formidable — {2}{R}: Crater Elemental has base power 8 until end of turn. Activate only if creatures you control have total power 8 or greater.

Thunderkin Awakener

Haste
Whenever Thunderkin Awakener attacks, choose target Elemental creature card in your graveyard with toughness less than Thunderkin Awakener's toughness. Return that card to the battlefield tapped and attacking. Sacrifice it at the beginning of the next end step.

Amplifire

At the beginning of your upkeep, reveal cards from the top of your library until you reveal a creature card. Until your next turn, Amplifire's base power becomes twice that card's power and its base toughness becomes twice that card's toughness. Put the revealed cards on the bottom of your library in a random order.

Fatal Frenzy

Until end of turn, target creature you control gains trample and gets +X/+0, where X is its power. Sacrifice it at the beginning of the next end step.

Mountain

Runaway Steam-Kin

Whenever you cast a red spell, if Runaway Steam-Kin has fewer than three +1/+1 counters on it, put a +1/+1 counter on Runaway Steam-Kin.
Remove three +1/+1 counters from Runaway Steam-Kin: Add {R}{R}{R}.

Terra Ravager

Whenever Terra Ravager attacks, it gets +X/+0 until end of turn, where X is the number of lands defending player controls.

Meekstone

Creatures with power 3 or greater don't untap during their controllers' untap steps.

Forgotten Cave

Forgotten Cave enters tapped.
{T}: Add {R}.
Cycling {R} ({R}, Discard this card: Draw a card.)

Lightning Serpent

Trample, haste
Lightning Serpent enters with X +1/+0 counters on it.
At the beginning of the end step, sacrifice Lightning Serpent.