Algalon's abilities

Algalon the Observer is the Hard-Mode only boss of Ulduar. The biggest problem with this boss is the time you have to train on him, you are only allowed to fight him one hour each week! After that, Algalon will despawn and you will have to wait for the next week before you can try to kill him again.
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Spell

Cosmic Smash
Calls an abyssal boulder from the sky, dealing 35613 to 41387 Fire damage.

Black Hole Explosion
15675 to 17325 Shadow damage inflicted to enemies. Instant

Quantum Strike
Strikes at an enemy, inflicting 15675 to 17325 Physical damage. 5 yd range

Phase Punch
Massive blow that inflicts 8788 to 10212 damage and slowly fades the target to another plane of existence. 5 yd range

Big Bang
Inflicts 107250 to 112750 Physical damage to nearby enemies. 8 sec cast, 3 sec cooldown

Loot Table

• 239 Dagger Spell Hit Main Hand - Starshard Edge
• 239 Plate Tank Legs - Legplates of the Endless Void

Quest Rewards

Algalon is the objective of the quest Heroic: All Is Well That Ends Well, after delivering the reply-code to Rhonin in Dalaran you will be able to choose one of the following rewards.

Achievements

Heroic Mode (25 Players)

Realm First! Celestial Defender
Participated in the realm first defeat of Algalon the Observer on Heroic Difficulty.
Title Reward: The Celestial Defender

Heroic: Observed
Defeat Algalon the Observer on Heroic Difficulty without any raid member dying to Algalon at any point during that raid lockout period.
Title Reward: The Astral Walker

Heroic: Supermassive
Defeat Algalon the Observer while destroying 4 Black Holes within 10 seconds on Heroic Difficulty.

He Feeds On Your Tears
Defeat Algalon the Observer on Normal Difficulty without any raid member dying to Algalon at any point during that raid lockout period.

Normal Mode (10 Players)

Herald of the Titans
Defeat Algalon the Observer on Normal Difficulty without anyone in the raid wearing any equipment with an item level higher than 226.
Title Reward: Herald of the Titans

Observed
Defeat Algalon the Observer on Normal Difficulty.
Title Reward: Starcaller

Supermassive
Defeat Algalon the Observer while closing 3 Black Holes within 10 seconds on Normal Difficulty.

He Feeds On Your Tears
Defeat Algalon the Observer without any raid member dying on Normal Difficulty.

Screenshots

Thanks to Wraith for these screenshots.

Video