Ambitious Dragonborn

This creature enters with X +1/+1 counters on it, where X is the greatest power among creatures you control and creature cards in your graveyard.

Bhaal's Invoker

Scorching Ray — {8}: This creature deals 4 damage to each opponent.

Thrakkus the Butcher

Trample
Whenever Thrakkus attacks, double the power of each Dragon you control until end of turn.

Skanos Dragonheart

Whenever Skanos Dragonheart attacks, it gets +X/+X until end of turn, where X is the greatest power among other Dragons you control and Dragon cards in your graveyard.
Choose a Background (You can have a Background as a second commander.)

Vrondiss, Rage of Ancients

Enrage — Whenever Vrondiss is dealt damage, you may create a 5/4 red and green Dragon Spirit creature token with "When this token deals damage, sacrifice it."
Whenever you roll one or more dice, you may have Vrondiss deal 1 damage to itself.

Avenging Hunter

Trample
When this creature enters, you take the initiative.

Rivaz of the Claw

Menace
{T}: Add two mana in any combination of colors. Spend this mana only to cast Dragon creature spells.
Once during each of your turns, you may cast a Dragon creature spell from your graveyard.
Whenever you cast a Dragon creature spell from your graveyard, it gains "When this creature dies, exile it."

Akul the Unrepentant

Flying, trample
Sacrifice three other creatures: You may put a creature card from your hand onto the battlefield. Activate only as a sorcery and only once each turn.

Korlessa, Scale Singer

You may look at the top card of your library any time.
You may cast Dragon spells from the top of your library.

Lozhan, Dragons' Legacy

Flying
Whenever you cast an Adventure or Dragon spell, Lozhan deals damage equal to that spell's mana value to any target that isn't a commander.

Renari, Merchant of Marvels

You may cast Dragon spells and artifact spells as though they had flash.
Choose a Background (You can have a Background as a second commander.)

Goddric, Cloaked Reveler

Haste
Celebration — As long as two or more nonland permanents entered the battlefield under your control this turn, Goddric is a Dragon with base power and toughness 4/4, flying, and "{R}: Dragons you control get +1/+0 until end of turn." (It loses all other creature types.)