Thunderbreak Regent

Flying
Whenever a Dragon you control becomes the target of a spell or ability an opponent controls, this creature deals 3 damage to that player.

Reckless Barbarian

Firespitter Whelp

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

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.")

Dragonstorm Globe

Each Dragon you control enters with an additional +1/+1 counter on it.
{T}: Add one mana of any color.

Manaform Hellkite

Flying
Whenever you cast a noncreature spell, create an X/X red Dragon Illusion creature token with flying and haste, where X is the amount of mana spent to cast that spell. Exile that token at the beginning of the next end step.

Parapet Thrasher

Flying
Whenever one or more Dragons you control deal combat damage to an opponent, choose one that hasn't been chosen this turn —
• Destroy target artifact that opponent controls.
• This creature deals 4 damage to each other opponent.
• Exile the top card of your library. You may play it this turn.

Corroding Dragonstorm

When this enchantment enters, each opponent loses 2 life and you gain 2 life. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
When a Dragon you control enters, return this enchantment to its owner's hand.

Defiant Thundermaw

Flying, trample
Whenever a Dragon you control attacks, it deals 2 damage to any target.

Invasion of Tarkir

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, reveal any number of Dragon cards from your hand. When you do, this Siege deals X plus 2 damage to any other target, where X is the number of cards revealed this way. (X can be 0.)