Formerly the most difficult classic 40 man raid dungeon in World of Warcraft, the release of World of Warcraft: Wrath of the Lich King saw Naxxramas being moved from Eastern Plaguelands to Dragonblight in Nothrend. It has since been changed from a 40 man raid to a 10 and 25 man dungeon. The instance is identical in design, but AI tweaks have been made to the bosses and NPC's.
Instead of being the last (and hardest) instance like it was in classic WoW, it is the first (and easiest) 10/25 man instance in Wrath of the Lich King. Outrage from the fanbase of WoW have even been heard from the lack of difficulty in Naxxramas.
Blizzard has since made attempts to make the game still easy for the people that want it like that, but have also added "Hard Modes" to certain bosses in newer raid instances to satisfy the players that want a challenge.
Naxxramas consists of four quarters, the Arachnid, Plague, Military, and Construct Quarters, as well as a final section known as the Frostwyrm Lair, where both Kel' Thuzad and Sapphiron reside. The Frostwyrm Lair can only be accessed once all four quarters have been cleared.
The complete list of bosses in Naxxramas are as follows:
|Arachnid Quarter||Plague Quarter||Military Quarter||Construct Quarter||Frostwyrm Lair|
| Anub Rekhan || Noth the Plaguebringer|| Instructor Razuvious|| Patchwerk|| Sapphrion |
| Grand Widow Farelina|| Heigan the Unclean|| Gothik the Harvester|| Grobbulus|| Kel'Thuzad|
| Maexxna|| Loatheb|| The Four Horsemen|| Gluth|| --|
| --|| --|| --|| Thaddius|| --|