If ANYTHING other then the Hunter gets on the aggro list of the demon
it will despawn for 3 hours.
Source: http://www.neoseeker.com/world-warcraft ... -epic.html
If any other class aggros it first, the demon will unleash a deadly AoE spell that will kill the person(s) in question. Saw that with my own eyes – people only had time to say “wtf”. After the 15 minutes are gone (demon won’t despawn during a fight) the demon despawns, the respawn timer being very long – reportedly about 3 hours.
Source: http://free-zg.t-com.hr/tlovey/epic.htm
Once spawned, you will have a 20 minute window to kill the deamon, after this time he will despawn for 15 minutes.
Source: http://wowwiki.wikia.com/Quest:Stave_of_the_Ancients
I don't know if the 7 hour respawn timer is true on Nostalrius but I can only find this 3 hour respawn timer for the case when SOMEONE ELSE attacks the demons and causes them to despawn. What is the actual respawn time on the demons when a hunter successfully kills them on Nostalrius and where did the designers of this server's epic hunter quest get sources to prove such long respawn times?