Aggonar

Aggonar was a pit lord who resided in Outland until he was killed. Later he appears in Argus.

Burning Crusade
When the pit lord Aggonar died, his fel blood poured into the sacred springs of the draenei, fouling the very essence of the holy water. They would now be known as the Pools of Aggonar, where fetid creatures spawn. The pools are the location of the Altar of Aggonar, the still skeleton of the pit lord, and the man'ari Arazzius the Cruel who leads the Burning Legion in Hellfire Peninsula.

Legion
Aggonar had since reformed in the Twisting Nether, returning to the Annihilan Pits on Argus, from where the pit lords assaulted the Krokul Hovel in Krokuun. Aggonar was defeated by High Exarch Turalyon, Alleria Windrunner, and an adventurer from Azeroth.

Abilities

 * Felfire Ward - Shields the target in fires of the Seat of Annihilation, making the caster immune to all damage
 * Glaive Blast - Inflicts Fire damage to all enemies within 10 yards of the impact.
 * Glaive Blast
 * Grip of the Pit King - Immobilizes nearby enemies with fel magic, rendering them unable to act.

Objective of

 * A Strike at the Heart

Trivia

 * The quest Cleansing the Waters claims that Aggonis, a mo'arg felguard, is an offspring of Aggonar, yet it's unknown if he is a direct son or a fel-sworn of another race corrupted by this pit lord.
 * Based on his title, Aggonar seems to be the ruler of the Annihilan Pits on Argus.