The adds are not connected to crystals (to my knowledge anyway). You simply need someone watching for crystals and call it in raid then back away when they spawn or if your like some guilds who use 15 clerics in a raid *roles eyes*, you can eat it and keep on dps. There is suposely a way to slow down the crystals that drop from rumors Ive heard but if there is I cant find it, nore has it mattered.
And honest to god there really isnt much strat at all to this raid, the absolute make or break part is your clerics learning how to heal around a 10 sec interupt. you will beat this when that happens.
You can CC drakes or you can kill them. Its been a mixture pretty even between the guilds that have beat him, some kill, some CC. Our guild perfers to kill them. We simply take 1 knight group a bit away from kera and keep off his agro. At 75% drakes start spawning. A couple knights bring them to the "Add tank" and that group kills the drakes. At 40% when the other dragons start spawning in the event this CC group can now go dps Kera. You will get no more adds. Of course if you chose to CC the wyverns rather than kill then that group is locked up for the entire raid.
At 30% Kera goes berserk. He rapes. He "can" hit for 20k + at this point. This is when your guild needs to use their big discs, not before. Get him down asap. The fight is over at 5%. You dont kill him. His family ties him up so to speak. So burn to 5% and you win.
Of all the AE's you can stop them all til 30% with the drake commands (which I dont know we use casters for that sorry), but I do suggest to you not stopping the Tailrake, and giving your raid mana each time you can. Your casters (clerics) should end the fight almost full mana. Which maens they have no worry at all about going oom in the fight and can just consentrate on working around the 10 sec interupt and you win.