Phase 1 :
The first tank positions the boss with his head to the left (or right) but preferably not facing the balcony. Tank ) She also Icy Grip's you to herself before casting Blistering Cold which has a 5 second cast time.Another thing to watch out is Permeating Chill, you might wanna stop DPS'ing if the stacks get too high.
Phase 2 ( Air Phase ) :
The tanks have the same job as the DPS and healers, if you get Frost Beacon stay 11 yards away from everyone but preferably close to the other beaconed guy (10 yards away). (Tip : Use smokes or lights and place them on the ground so the beaconed ones can go to their places without hesitation, it's VERY HELPFUL, use it!) And of course LoS the Frost Bomb (DPS the tombs to 10% then wait till Sindragosa gets down to take her. ( She will cast 4 Frost Bombs during this phase so make sure you have your Frost tombs at about 10% so you can LoS the spells and then quickly release your friends).
Phase 3:
The hardest phase. One new spell Mystic Buffet acts as a soft enrage timer.
This spell is VERY DANGEROUS, that's where two tanks become very handy, when the MT has 3-4 Stacks the OT ( with 0 Debuffs because he has been in behind the Frost Tombs, LoS) taunts. The MT goes behind an Icy Tomb to remove Mystic Buffet. Rinse and Repeat.

Before getting to other jobs, I just want to add that in phase 3 Sindragosa won't fly in the air anymore but she WILL cast all her spells from Phase 1 + Mystic Buffet and she WILL freeze people into Icy tombs which will have to be killed as soon as tanks have had their debuff reset.

Healers:

Phase 1 :
Frost Aura it's a passive spell, this fight will require A lot of healing is required. Tanks will usually not get a lot of damage before phase 3 , So healers should focus mainly on DPS'ers at the moment ( Sindragosa hits for 12k ~ on me and I can evade her Frost Breath).
It's important NOT to cast when you have Unchained Magic because it will result in damage and (I'm not totally sure but I think there is also a Silence).
Phase 2 :
Most important thing here is to FULLY heal the beaconed people or they WILL die in the frost tomb ( they can't be healed while inside of the tombs), Healers LoS the spell Sindragosa casts and heal people who got hit but of course normally they shouldn't get hit. After being released, the beaconed ones will probably be low on health, make sure to fully heal them.
Phase 3 :
VERY Stressing phase, Tanks will now take @#$% loads of damage and the same goes to the DPS'ers.
This is just a DPS race so your main job is to just AoE heal everyone or spam heals on the MT-OT because Sindragosa's spells can now hit the tanks for about 35-40k damage.

DPS:

Phase 1 :
Normal phase and easy just DPS the boss without being at her tail and watch out when you get Permeating Cold (spell tool tip in the tank section) , you will have to stop attacking. Nothing special, move on to phase 2. Casters you should also watch out for Unchained Magic (spell tool tip in healer section).
Phase 2:
Easy phase too, make sure you get the frost tombs to 10% (or even 30% because Dots can finish the tomb) and stop DPS'ing till Sindragosa casts her 4 spells. Again, Make sure you have smokes or lights on the floor to indicate where to stand , it's VERY Helpful.
Phase 3 :
I thing thats 35% or less (abour 3500k/4500k)
DPS race but there are also A lot of things to do, first of all Sindragosa will keep all her Phase 1 spells + She will beacon people + a New Spell (Mystic Buffet).
We did it like this : Ranged DPS the boss always but refresh debuffs at about 5 stacks.
Melee release your friends from the tombs BUT not before the tanks have had their debuffs reset as said before, there will be a lot of tank change and tank damage.

Just one more thing, if you get beaconed, make sure you get away from your friends(or go to a designated place to stay) or it's an instant wipe.

I stated almost everything I think, hope this helps.

PS : It might seem hard but after 4-5 wipes you get the heck of it.
Phase 1 and 2 weren't a problem last night, Phase 3 well, It's the hard part, try to get through it.
The most important tip from yestarday "DON'T PANIC