Finally did it about a month ago. Have a Tank/Healer/Caster/Caster/Melee/Melee group. Didn't have just enough DPS to get it done the brute force method. I was coming up short by 1 or 2 pops of the Elders.
So I mapped where two of the Elders popped that were next to each other. Placed a caster near each of those locations. Had tank and healer and melee-dps1 positioned between the 2 Elder pop locations. Had melee-dps2 start the script and then run to where the Tank/Healer/Melee-dps 1 was. Tank engages and pulls Shardrahn back to where the two casters are in range. Group engages.
It didnt take that many attempts before the 1st and 2nd pops were where the two casters were located ( the pop locations and order are random). When the notification appeared, I would just move the caster into the aura. This gave me about 10-15 more seconds which is all that I needed.
Couple thing that I assumed, but could be wrong:
(1) DPS really only needs to really go hard once Shardrahn is at around 75% which is when the first notification hits
(2) It seems that the casters would have to be originally outside of the aura and then move into it in order to stop the Elder from spawning. I originally tried to start the above with the two casters in exactly the same spot where the auras spawn, but it didnt seem like this worked. It was only when I manually moved them into the aura once it spawned that I was successful.