Arena Athlete

Heroic — Whenever you cast a spell that targets Arena Athlete, target creature an opponent controls can't block this turn.

Tremor

Tremor deals 1 damage to each creature without flying.

Tooth and Claw

Sacrifice two creatures: Create a 3/1 red Beast creature token named Carnivore.

Humble Defector

{T}: Draw two cards. Target opponent gains control of Humble Defector. Activate only during your turn.

Frostling

Sacrifice Frostling: It deals 1 damage to target creature.

Syr Carah, the Bold

Whenever Syr Carah, the Bold or an instant or sorcery spell you control deals damage to a player, exile the top card of your library. You may play that card this turn.
{T}: Syr Carah deals 1 damage to any target.

Tormenting Voice

As an additional cost to cast this spell, discard a card.
Draw two cards.

Lightning Strike

Lightning Strike deals 3 damage to any target.

Meteor Golem

When Meteor Golem enters the battlefield, destroy target nonland permanent an opponent controls.

Breaker of Armies

All creatures able to block Breaker of Armies do so.

Skyscanner

Flying
When Skyscanner enters the battlefield, draw a card.

Claws of Valakut

Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control and has first strike.

Shock

Borderland Marauder

Whenever Borderland Marauder attacks, it gets +2/+0 until end of turn.

Crash Through

Creatures you control gain trample until end of turn. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)
Draw a card.

Galvanic Relay

Exile the top card of your library. During your next turn, you may play that card.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Zap deals 1 damage to any target.
Draw a card.

Satyr's Cunning

Create a 1/1 red Satyr creature token with "This creature can't block."
Escape—{2}{R}, Exile two other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Rile

Rile deals 1 damage to target creature you control. That creature gains trample until end of turn.
Draw a card.

The Flame of Keld

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Discard your hand.
II — Draw two cards.
III — If a red source you control would deal damage to a permanent or player this turn, it deals that much damage plus 2 to that permanent or player instead.

Rionya, Fire Dancer

At the beginning of combat on your turn, create X tokens that are copies of another target creature you control, where X is one plus the number of instant and sorcery spells you've cast this turn. They gain haste. Exile them at the beginning of the next end step.