Before the Great Cataclysm that divided the planet, Aion created the race of Balaur to rule the world of Atriea. However, they became complacent and hungry for power. Aion was forced to create the Empyrean Lords in retaliation to the aggressive nature of the dragon race. So began the war and the events leading to the world's ultimate division.
 

The Balaur are one of three factions involved in Aion's unique PvPvE system. The Balaur are a server-controlled race of NPCs. The Balaur, as a whole, represent the most formidable non-player characters in the world of Atreia, a threat second only to the players of the opposing faction. Their defeat in battle also results in, or is tied directly to, the most desirable items in the game.

These NPCs are found almost exclusively in the Abyss, and will attack players of both factions on sight. The Balaur control castles and other locations of interest in the Abyss and may also seek to conquer areas that are held by the Asmodian or Elyos. In addition to stationary troops and sentries found defending castles and artifacts, the dragons also control massive flying airships known as "Dreadgions."

These airships are the most awesome weapon in the Balaur arsenal; able to fire powerful beams of light, drop shock-troops, and possibly do other terrible things not yet observed. They make for the quick death of single players or even small groups lacking a full raid force.


Official Information
The Producer of Aion, Ju-hyun Jang, about the Balaur:

"The Balaur are a server-controlled NPC faction, so players cannot choose to play them.
However, just because they are controlled by the server doesn't mean they are stupid; they can make choices, and players will never quite know what they are going to do.
For example, imagine a castle siege-style scenario, where one of the player factions, the Asmodians, is attacking the Elyos faction's castle. In the middle of this siege, the Balaur may appear.

When they arrive, no-one will know what they are going to do. They may have previously helped the Asmodians, but that doesn't matter; in the siege, they might betray them and help the Elyos. Or they might help the Asmodians to siege the Elyos' castle. Or... they might try and take the castle for themselves, fighting against both the Elyos and the Asmodians.

The important thing to realize is that the Balaur are not typical NPCs. They are the third faction in the game, and they have free will, which makes them very unpredictable."
Etymology
Balaur is a creature from Romanian folklore, similar to a dragon. A balaur is quite large, has fins, feet, and is polycephalous (it usually has three, sometimes seven, or even twelve serpent heads). As a traditional character which is found in most Romanian fairy tales, it represents Evil and must be defeated by Făt-Frumos (a knight hero in Romanian folklore) in order to release the Princess.