Abaddon

General
Abaddon is the name of a dark fallen god that was outcast by the Gods of Tyria long ago and exiled to the Realm of Torment. He was formerly the god of water and knowledge.

The outcasting of Abaddon
Abaddon was formerly the god of water and knowledge. When the gods gave the sentient species of Tyria (world) the gift of magic, it was Abaddon who represented the gods and handled the actual distribution. However, Abaddon gave out this gift a little too freely and indiscriminately, which fueled the greed that caused the sentient races to abuse it and wage massive wars against each other.

King Doric went to Arah and begged the gods to bring peace. Against the opposition of Abaddon, the other five gods created the Bloodstones to split up the four schools of magic, which would suppress its abuse.

Abaddon was angered by this, and he gathered his strongest followers, the Margonites, to assault the weak spot of the Rift so he could overthrow the other five gods. However, while Abaddon was strong enough so that the joint forces of two other gods could not defeat him, he still could not withstand the powers of five gods united. In the end he was defeated and imprisoned in the Realm of Torment, never to interfere with worldly matters again. The site of that great battle is now knows as the the Mouth of Torment.

After the war, the five gods erased all mentioning of Abaddon and his deeds from monuments and historical records. Curiously, there is still a location named Abaddon's Mouth.

Trivia

 * Abaddon is Hebrew and means "doom" or "destruction". In the Bible it denotes both a location (the underworld / hell), as well as a creature (a demon / satan). For more information see the Wikipedia article about Abaddon.
 * Concept art for Abaddon has a face heavily resembling that of the Mursaat's jade minions.

Remaining influences

 * The Day shall come when the Lord of Secrets
 * Will be freed of his Tormented Prison
 * When the other gods will quail before his power
 * And Night will fall on the living world
 * - Scriptures of Abaddon

In the Nightfall campaign, Spearmarshal Kormir suspects that Varesh Ossa and General Kahyet, her respected mentor and loyal officer, are worshippers of this deity and are trying to bring about its return.

It also seems that his forces were behind the trouble at the Dragon Festival and the Ruins of the Tombs of the Primeval Kings as a way to invade Tyria and Cantha.

The Scriptures of Abaddon
This inscription can be found on the empty Statue pedestal of Abaddon in the Gates of Torment mission:

Location
Realm of Torment
 * Abaddon's Gate (Mission)