Chandra's Pyreling

Whenever a source you control deals noncombat damage to an opponent, Chandra's Pyreling gets +1/+0 and gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Cavalcade of Calamity

Whenever a creature you control with power 1 or less attacks, Cavalcade of Calamity deals 1 damage to the player or planeswalker that creature is attacking.

Forbidden Friendship

Create a 1/1 red Dinosaur creature token with haste and a 1/1 white Human Soldier creature token.

Scorch Spitter

Whenever Scorch Spitter attacks, it deals 1 damage to the player or planeswalker it's attacking.

Goblin Arsonist

When Goblin Arsonist dies, you may have it deal 1 damage to any target.

Heartfire

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

Chandra, Acolyte of Flame

0: Put a loyalty counter on each red planeswalker you control.
0: Create two 1/1 red Elemental creature tokens. They gain haste. Sacrifice them at the beginning of the next end step.
−2: You may cast target instant or sorcery card with mana value 3 or less from your graveyard. If that spell would be put into your graveyard, exile it instead.

Castle Embereth

Castle Embereth enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Tin Street Dodger

Haste
{R}: Tin Street Dodger can't be blocked this turn except by creatures with defender.

Fervent Champion

First strike, haste
Whenever Fervent Champion attacks, another target attacking Knight you control gets +1/+0 until end of turn.
Equip abilities you activate that target Fervent Champion cost {3} less to activate.

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.