From WoWWiki
The Immortal is an end game raid achievement for killing all of the bosses in Naxxaramas without any members dying. Completing this achievement is criteria for the meta achievement 
[Glory of the Raider (25 player)].
Q & A
Bornakk answered some questions about the achievement on the forums: [1]
- Must you be present for all the boss kills, or just KT?
If you do not die on any other bosses and get to Kel'thuzad, you could (conceivably) sell slots and bring in random people for Kel'thuzad and (assuming nobody dies), they would get the achievement.
- If you were only present for KT and no one died during KT, would you get the achievement?
If anybody died on any boss, the raid ID is no good.
- Are wipes included, or do deaths only matter for actual boss kills?
- Wipes include deaths, so this makes the raid ID no good as well.
- Deaths on trash are fine, deaths on bosses nullify the raid ID for the whole week it is active.
See also
References
External links
StratFu Avoid common Naxx strategy mistakes and achieve The Immortal
The Immortal
[Glory of the Raider (25 player)].
Bornakk answered some questions about the achievement on the forums: [1]
[The Undying]
StratFu Avoid common Naxx strategy mistakes and achieve The Immortal
