Both alys normal and hc is soloable still, your problem is you're too slow / server lag on rings, if a ring spawns and alys has flown too far ahead, you have to forget that ring, or rapidly fly through it, instead of waiting for the stack proc thing.
It's something you have to judge for yourself, if your double dipping rings the despawn will happen alot, for example i at to double dip every other ring to avoid despawning.
EDIT: saw your last comment, i don't play a Spriest but on beta Beth was done with a bug i think, can go try her, see if she hits way too hard or such, you will need to be quite experienced i would have thought with soloing to attempt anymore than alys though, other than that the only other one i can see being done is rhyolith, its basically a 0 tank fight till P2, and he hits weak on me as a tank in P2 so perhaps doable by yourself, the adds will hurt though, so rapid dps is a must ^^.
Last edited by TwentyTwelve; 2012-11-04 at 12:42 PM.
I've been killing her with my shadow priest friend for the past few weeks and from our experience you will despawn her whenever she drops her last air ring before swooping down to fly low. It seems this ring gets placed somewhere on the very "edge" of her room and if you go for it there's a very good chance you will leave he room and evade her. So we simply skip that ring and she has never given us any issues that way.
Same happened to me but only when she was going down in phase 1 to do the sweep with her legs. You have to stay close to her and keep attacking her when she is going down. Otherwise she despawns (happened two times to me). On the third I just kept attacking her, not minding to get the ring that's usually placed very when she is about to go down. Then I just follow her while she does the sweep, go through the 3 rings she put up and fly again.
I brought her to 35% in p1. Left the area to park my char just outside it (usually where you would gather with the raid untill you were ready to pull adds). This part will become healing intensive so make sure you spam it.