Draconic Debut

Draconic Debut deals X damage to any target.
The next Dragon creature spell you cast costs {X} less to cast.

Mountain

Terror of the Peaks

Flying
Spells your opponents cast that target this creature cost an additional 3 life to cast.
Whenever another creature you control enters, this creature deals damage equal to that creature's power to any target.

Dragonlord's Servant

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

Gadrak, the Crown-Scourge

Flying
Gadrak can't attack unless you control four or more artifacts.
At the beginning of your end step, create a Treasure token for each nontoken creature that died this turn. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Sarkhan, Wanderer to Shiv

+1: Dragon cards in your hand perpetually gain "This spell costs {1} less to cast," and "You may pay {X} rather than pay this spell's mana cost, where X is its mana value."
+1: Conjure a card named Shivan Dragon into your hand.
−2: Sarkhan, Wanderer to Shiv deals 3 damage to target creature.

Treasure

{T}, Sacrifice this token: Add one mana of any color.

Minion of the Mighty

Menace
Pack tactics — Whenever this creature attacks, if you attacked with creatures with total power 6 or greater this combat, you may put a Dragon creature card from your hand onto the battlefield tapped and attacking.

Drakuseth, Maw of Flames

Flying
Whenever Drakuseth attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Inferno of the Star Mounts

This spell can't be countered.
Flying, haste
{R}: Inferno of the Star Mounts gets +1/+0 until end of turn. When its power becomes 20 this way, it deals 20 damage to any target.

Fearsome Whelp

Flying
At the beginning of your end step, each Dragon card in your hand perpetually gains "This spell costs {1} less to cast."

Goldspan Dragon

Flying, haste
Whenever this creature attacks or becomes the target of a spell, create a Treasure token.
Treasures you control have "{T}, Sacrifice this artifact: Add two mana of any one color."

Orb of Dragonkind

{1}, {T}: Add two mana in any combination of colors. Spend this mana only to cast Dragon spells or activate abilities of Dragons.
{R}, {T}, Sacrifice this artifact: Look at the top seven cards of your library. You may reveal a Dragon card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.