Soul-Scar Mage

Prowess
If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Mountain

Viashino Pyromancer

When this creature enters, it deals 2 damage to target player or planeswalker.

Goblin Chainwhirler

First strike
When Goblin Chainwhirler enters, it deals 1 damage to each opponent and each creature and planeswalker they control.

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.

Monastery Swiftspear

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

Shock

Lightning Strike

Lightning Strike deals 3 damage to any target.

Wizard's Lightning

This spell costs {2} less to cast if you control a Wizard.
Wizard's Lightning deals 3 damage to any target.

Ghitu Lavarunner

As long as there are two or more instant and/or sorcery cards in your graveyard, this creature gets +1/+0 and has haste. (It can attack and {T} as soon as it comes under your control.)

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}.