Missing or Dead Bosses in Raid Instance

If you enter a raid instance and some or all the bosses are dead, it means you shared a strict instance-based lockout with a group, and they cleared the raid without you.

In strict instance-based lockouts, progress is tied to a fixed instance ID. Once tied to an instance ID, you may not enter any other versions of that raid of that difficulty until your raid lock resets.

• If other players complete that instance while you are absent, the instance will be empty for you as well, because progress is tied to the instance, and not your character.
• You may not switch between 10-player and 25-player raid size once locked to one size or the other (does not apply to Mythic which is 20-player only)

The strict instance-based lockout applies to:

• All Classic and Burning Crusade raids:
  Sunwell Plateau, Tempest Keep, Karazhan, Black Temple, Battle for Mount Hyjal, Magtderidon's Lair, Gruul's Lair, Serpentshrine Cavern, Temple of Ahn'Qiraj, Ruins of Ahn'Qiraj, Blackwing Lair, Molten Core
• The Heroic difficulty of all Wrath of the Lich King raids:
  Ruby Sanctum, Icecrown Citadel, Onyxia's Lair, Trial of the Crusader, Ulduar, Vault of Archavon, Naxxramas, Obsidian Sanctum, Eye of Eternity
• The Heroic difficulty of all Mists of Pandaria raids, except Siege of Orgrimmar:
  Throne of Thunder, Terrace of Endless Spring, Heart of Fear, Mogu'shan Vaults
• All Mythic difficulty raids.

In Mythic difficulty, you are bound to the raid ID. This means if you join a Mythic raid, defeat the first boss (thereby binding you to that Mythic raid ID) and leave; you'll return to the same raid. If the raid continues on to defeat bosses 2, and 3 while you were gone, you will return to the raid with those bosses already defeated.

For that reason, it is important to stick together with the same group of people as much as possible for Mythic difficulty.

When joining a Mythic raid that's already in-progress, read the notification box that pops up carefully. It'll let you know how many bosses have already been defeated and ask for confirmation to be saved to that raid. If something's not adding up, you can refuse to be saved and be teleported out without being saved.