Nihilum and Death & Taxes Guild reached Kel’Thuzad boss in Naxxramas.  However, both guilds reported publically that after the first wipe, when both guilds returned to Kel’Thuzad’s chamber he was there no more. Despawned and did never return.

Tigole replied that this despawn shouldn’t happen and it is not intended. Sympathies to both guilds for the loss of materials. Keep it up! Image by Bloodshot @ Korgath (Death & Taxes Guild)

Tigole: “He should not be despawning. We’ll check it out and try to get it fixed ASAP.  as soon as we can reproduce the bug internally, figure out why it’s happening and apply a fix to live servers. We’re not trying to prevent anyone from beating the encounter. To be honest, we expected Sapphiron to die the same night the 4 Horsemen were downed. Kel’Thuzad was designed to be defeated by players. We *want* people experiencing the content. I am pretty happy with Naxxramas overall. Yes, we’ve had some bugs and a few mistuned encounters (Grobbulus). But overall the feedback has been very positive. Players are having fun. Do we hope to do a better job in the future? Of course—always. Does Naxxramas need to “last” until the Burning Crusade comes out? No. Kill the bosses—enjoy the content. Burning Crusade will be out soon enough—and it rocks =P”