Mountain

Spider Manifestation

Reach
{T}: Add {R} or {G}.
Whenever you cast a spell with mana value 4 or greater, untap this creature.

Firebending Student

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Firebending X, where X is this creature's power. (Whenever this creature attacks, add X {R}. This mana lasts until end of combat.)

Firespitter Whelp

Flying
Whenever you cast a noncreature or Dragon spell, this creature deals 1 damage to each opponent.

Dragonlord's Servant

Dragon spells you cast cost {1} less to cast.

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.

Mox Jasper

{T}: Add one mana of any color. Activate only if you control a Dragon.

Embermouth Sentinel

When this creature enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top. If you control a Dragon, put that card onto the battlefield tapped instead.

Flush Out

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