Molten Exhale

You may cast this spell as though it had flash if you behold a Dragon as an additional cost to cast it. (To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.)
Molten Exhale deals 4 damage to target creature or planeswalker.

Narset's Rebuke

Narset's Rebuke deals 5 damage to target creature. Add {U}{R}{W}. If that creature would die this turn, exile it instead.

Overwhelming Surge

Choose one or both —
• Overwhelming Surge deals 3 damage to target creature.
• Destroy target noncreature artifact.

Rescue Leopard

Whenever this creature becomes tapped, you may discard a card. If you do, draw a card.

Reverberating Summons

At the beginning of each combat, if you've cast two or more spells this turn, this enchantment becomes a 3/3 Monk creature with haste in addition to its other types until end of turn.
{1}{R}, Discard your hand, Sacrifice this enchantment: Draw two cards.

Treasure

Sarkhan, Dragon Ascendant

When Sarkhan enters, you may behold a Dragon. If you do, create a Treasure token. (To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.)
Whenever a Dragon you control enters, put a +1/+1 counter on Sarkhan. Until end of turn, Sarkhan becomes a Dragon in addition to its other types and gains flying.

Seize Opportunity

Choose one —
• Exile the top two cards of your library. Until the end of your next turn, you may play those cards.
• Up to two target creatures each get +2/+1 until end of turn.

Spirit

Fortress Kin-Guard

When this creature enters, it endures 1. (Put a +1/+1 counter on it or create a 1/1 white Spirit creature token.)

Warrior

Shock Brigade

Menace (This creature can't be blocked except by two or more creatures.)
Mobilize 1 (Whenever this creature attacks, create a tapped and attacking 1/1 red Warrior creature token. Sacrifice it at the beginning of the next end step.)

Shocking Sharpshooter

Reach
Whenever another creature you control enters, this creature deals 1 damage to target opponent.

Stadium Headliner

Mobilize 1 (Whenever this creature attacks, create a tapped and attacking 1/1 red Warrior creature token. Sacrifice it at the beginning of the next end step.)
{1}{R}, Sacrifice this creature: It deals damage equal to the number of creatures you control to target creature.

Stormscale Scion

Flying
Other Dragons you control get +1/+1.
Storm (When you cast this spell, copy it for each spell cast before it this turn. Copies become tokens.)

Stormshriek Feral

Flying, haste
{1}{R}: This creature gets +1/+0 until end of turn.

Flush Out

Discard a card. If you do, draw two cards. (Then shuffle this card into its owner's library.)

Stormshriek Feral // Flush Out

Summit Intimidator

Reach
When this creature enters, target creature can't block this turn.

Sunset Strikemaster

{T}: Add {R}.
{2}{R}, {T}, Sacrifice this creature: It deals 6 damage to target creature with flying.

Tersa Lightshatter

Haste
When Tersa Lightshatter enters, discard up to two cards, then draw that many cards.
Whenever Tersa Lightshatter attacks, if there are seven or more cards in your graveyard, exile a card at random from your graveyard. You may play that card this turn.

Tarkir: Dragonstorm