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 and known the Order of the Whispers as the God of Secrets.

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

The Casting Out of Abaddon
Abaddon was formerly the God of Water and Knowledge. When the gods gave the sentient races of Tyria 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. Although Abaddon was strong enough to defeat the joint forces of two gods, he still could not withstand the power of all 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 known as the the Mouth of Torment.

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

The Scriptures of Abaddon
This excerpt from the Scriptures of Abaddon can be found as an inscription on the empty Statue pedestal of Abaddon in the Gate of Madness mission:

Another section of the Scriptures is revealed in the Guild Wars Nightfall manual:


 * 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

Abaddon's fate
In the final mission of the Nightfall campaign, Abaddon is defeated, and begins to collapse. Kormir, using the gift granted to her by the avatars, absorbs his power and knowledge and becomes the Goddess of Truth.

Olias makes the following statement in Throne of Secrets
 * "Abaddon is dead. And I assure you, Grenth will not make the mistake that the other gods did. We will not hear from Abaddon again in this lifetime... or the next."

However, considering Dhuum's current status, this statement is suspect.

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

It also seems that his forces (along with the forces of Dhuum and Menzies) 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.

According to the Margonite Apostate, Abaddon attained his power by deposing an unnamed earlier god.

A mission in Tyria (the 2nd to last) is named after Abaddon. In Abaddon's Mouth, you try to reach the Door of Komalie.

Trivia

 * Abaddon is similar to the word "Avadon" in Hebrew which means "doom" or "destruction". In the Bible it denotes both a location (the underworld / hell), as well as a creature (the "Angel of the Abyss"). For more information see the Wikipedia article about Abaddon.
 * Standing on the bridge (or near to it) in Abaddon's Gate (Mission) and using the /dance emote before engaging Abaddon will cause him to do a little dance of his own (including a "raise the roof" move, the fingers-across-the-eyes move from the male warrior's dance (as seen being done by John Travolta and Uma Thurman in the movie Pulp Fiction), and the 'rock on' sign from the necromancer dance) before slaying your entire party. The video can be seen here. (Note that every party member must use the dance emote for Abaddon to start and that /dancenew does not trigger Abaddon's animations).''
 * Abaddon's appearance is homage to the disembodied-head-and-hands style of boss, which appears in numerous video games, including Star Fox (Andross), Chrono Trigger (Queen Zeal and one of the forms of Lavos), Ninja Gaiden 2 (Naga Sotuva), and Zelda: Ocarina of Time (Bongo Bongo).