World boss

This page contains a short overview of all world bosses in game. These bosses are considered raid bosses since it takes more than a party of 5 players to down them. Some people have roughly estimated their spawn rates:

Initial spawn:
 * Tuesday Night, very late (~1-5%)
 * Wednesday Night (50-80%)
 * Thursday Night (15-20%)

Respawn:
 * 2 days after previous kill (30%)
 * 3 days after previous kill (40%)
 * 4 days after previous kill (30%)

Server crashing or going down counts as that world boss having been killed, and starts its respawn timer

At the time of the testing, Azuregos/Lord Kazzak used to spawn a little earlier than the world dragons. The dragons spawn one unique per the 4 spawn locations, typically all at the same time. One continent being down without the other desyncs the dragons, possibly making them spawn duplicates. (Thus occasionally spawning 2 of the exact same bosses in different locations)

World bosses were phased out of Blizzard's design philosophy starting with Wrath. Cataclysm did introduce some small group mini-bosses, but nothing that requires a serious raid.

History of World Raid Bosses
Originally, Azuregos and Lord Kazzak were added early in WoW. They were two of WoW's greatest promotions of intraguild cooperation and interguild rivalry, as killing them required tracking their spawn, forming a raid, and beating the encounter AND the opposing faction (and at times same faction griefers). Their loot was also among the best at the time of their popularity.

Shortly before the Ahn'Qiraj event, the four Dragons of Nightmare were created, and added an entire new round of World Raid bosses. They were initially killed for having the best items for their slots, and later farmed for their nature resistant gear when it became apparent that some Temple of Ahn'Qiraj encounters required it. They were also involved in the Scepter of the Shifting Sands green piece questline.

As time passed, and Naxxramas came out without accompanying world raid bosses, the popularity of the world raid bosses began to fade.

With patch 2.0, Highlord Kruul began to terrorize Azeroth, in place of Lord Kazzak (and his Azeroth loot table).

After the Burning Crusade came out, two new world raid bosses were introduced, Doom Lord Kazzak and Doomwalker (there were others initially shown in databases as ?? bosses, including a rare spawn from a quest in Blade's Edge in which you can spawn a raid boss who flies away, but is unaggro-able. But currently it is accepted that there are 2 BC world raid bosses). The popularity of the two was short-lived. After a couple months it became apparent that loot off of Karazhan was on par or better, while not having the additional faction vs. faction griefing factor.

In BC WoW 2.2, world bosses were often left untouched for long periods of time. There were occasional guilds that use them as either practice for raiding, or undergeared guilds trying to gear up. But with the announcement by a blue that they did not plan to add additional world raid bosses (source?), the days of a world raid boss came to an end.

Blizzard did not add any world raid bosses for WOTLK. Cataclysm does contain some small group mini-bosses though.

Omen


Location: Moonglade Raid 40 Omen is a demon boss summoned in the Moonglade during the Lunar Festival.

Doom Lord Kazzak


Location: Hellfire Peninsula Raid 25 Former commander of the Burning Legion forces in the Blasted Lands, the former-Doomguard, now crowned Doom Lord Kazzak awaits with his formidable troops for the heroes of Azeroth to challenge his reign as Commander of the Burning Legion in Outland. He consumes the soul of all beings he slays to heal himself, casts a curse on players that makes their mana pools combust and if he isn't killed in 3 minutes, goes into his "supreme mode," allowing him to completely obliterate everything in his path.

Doomwalker


Location: Shadowmoon Valley - In front of The Black Temple Raid 25 Doomwalker is a powerful Fel Reaver sent by Kil'jaeden to assault the gates of the Black Temple in Shadowmoon Valley. He's a clear reminder for Illidan that Kil'jaeden hasn't forgotten about him...

Others - Cataclysm
Cataclysm did introduce some small group mini-bosses, but nothing that requires a serious raid. One for each new zone.

Akma'hat 
Location: Uldum Party 5 Drops Belt of a Thousand Gaping Mouths Akma'hat is a Tol'vir style colossus located in Uldum.

Garr
Location: Mount Hyjal Party 5 Drops Garr's Reinforced Girdle of Memories Garr is a lava elemental found to the west of Sulfuron Spire on Mount Hyjal. This guy seems to have survived our killing of him in molten core, apparently his falling apart into several chunks was merely a setback.

Julak-Doom 
Location: Twilight Highlands Party 5 Drops Vitreous Beak of Julak-Doom Julak-Doom is a merciless one controlling a flesh giant of the same name.

Mobus 
Location: Abyssal Depths Party 5 Drops Mobus's Dripping Halberd Mobus is a whale shark found circling the Abyssal Breach.

Xariona
Location: Deepholm Party 5 Drops Xariona's Spectral Gauntlets

Xariona is a twilight dragon roaming around the Temple of Earth.

Previous old bosses
These world bosses have been removed from World of Warcraft.

Dragons of Nightmare
In recent times, Ysera's most trusted lieutenants have been warped by a dark new power within the Emerald Dream. Now these wayward sentinels have passed through the Great Trees into Azeroth, intending to spread madness and terror throughout the mortal kingdoms.

Emeriss


Location: The Great Trees Raid 40 One of the Four Dragons corrupted by the Nightmare, Emeriss is a gruesome, rotting monstrosity. Along with his AoE Sleep, he also casts a disease which damages nearby allies, and turns the corpses of the dead into deadly mushrooms. And every 25%, he casts Corruption of Earth, a Shadow DoT that deals 100% damage to the players health over 8 seconds.

Lethon


Location: The Great Trees Raid 40 One of the Four Dragons corrupted by the Nightmare, Lethon has become exceedingly evil, enough so to darken the hue of his scales, and his eyes have also been forced open, an oddity amongst Green Dragons. He has a massive Shadowbolt Volley, and every 25% he extracts shades from his enemy that will heal him.

Ysondre


Location: The Great Trees Raid 40 One of the Four Dragons corrupted by the Nightmare, Ysondre's once beneficial healing powers have given way to dark magics. Casts an AoE Lightning Wave that deals direct Nature damage, and summons fiendish Druids every 25%.

Taerar


Location: The Great Trees Raid 40 One of the Four Dragons corrupted by the Nightmare, Taerar was perhaps the most affected of Ysera's lieutenants. His corporeal form has been shattered and he exists as a specter. Has an AoE Fear, and creates 3 Shades of himself every 25%.

Azuregos


Location: Azshara Raid 40 A mighty blue dragon who resides in the wilderness of Azshara, perusing over the countless magical artifacts there. He randomly teleports himself and all players within 30 feet a short distance, wiping aggro, casts a blizzard-like spell that eats mana, and occasionally puts up a magic reflection shield. Also, in order to prevent graveyard-zerging, he places a debuff on players that he kills. Any living players with this debuff will freeze whenever they go near him.

Highlord Kruul


Location: Blasted Lands Raid 40 Highlord Kruul is a doomguard boss who appears in various parts of Azeroth during the Dark Portal Opens event, introduced in patch 2.0.3. After the Dark Portal reopened, he officially replaced Lord Kazzak (now Doom Lord Kazzak in Outland's Hellfire Peninsula) as the Burning Legion's field commander in Azeroth, residing in the Tainted Scar in the Blasted Lands, southwest of the Portal.

He has since been removed from the game as of the release of The Burning Crusade.

Teremus the Devourer


Location: Blasted Lands Raid 10? Teremus is an immensely powerful black drake found in the Blasted Lands. He has an AoE Lifesteal, and wipes aggro when he uses a knockback attack. When he gets down to 20% health, he regenerates to full health, making him one of the most difficult and prolonged fights in the game.

He used to be a popular target for the makers of machinima, most frequently being kited by a hunter and a priest from the Blasted Lands to Stormwind or Ironforge, but as of some past patches, he is now chained to the Blasted Lands and will leash back when a player tries to kite him out of the zone.

As of Cataclysm, Teremus is no longer an elite mob but only rare, as which he is significantly weaker.