Onyxia is dead.

I thought she could only be ATTEMPTED every 5 days by the people in the group. If it's a 5 day respawn, that's going to SUCK a long time down the road. People will be camping the portal, waiting for the respawn so they can get her.

It's 5 days from the point of the group leaving the instance, or something like that. But multiple raid groups could do it at the same time.