Shock

Runaway Steam-Kin

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

Fervent Champion

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

Mountain

Ilharg, the Raze-Boar

Trample
Whenever Ilharg attacks, you may put a creature card from your hand onto the battlefield tapped and attacking. Return that creature to your hand at the beginning of the next end step.
When Ilharg dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Boulder Rush

Target creature gets +2/+0 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Rimrock Knight

Rimrock Knight // Boulder Rush

Stomp

Damage can't be prevented this turn. Stomp deals 2 damage to any target.

Bonecrusher Giant

Whenever this creature becomes the target of a spell, this creature deals 2 damage to that spell's controller.

Bonecrusher Giant // Stomp

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.

Risk Factor

Target opponent may have Risk Factor deal 4 damage to them. If that player doesn't, you draw three cards.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Purphoros, Bronze-Blooded

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Other creatures you control have haste.
{2}{R}: You may put a red creature card or an artifact creature card from your hand onto the battlefield. Sacrifice it at the beginning of the next end step.