This is a simple fight as MNK. I always go MNK and on the third cycle we always kill her. Could be faster but some of the other members are not yet geared to the i85+ position.

Here is what I do. On the second sisters (with tornados) MT pulls Garuda and Soprano to NW. Healers and Ranged stand SE and OT and my self (MNK) SW. I dps Chirada with the OT while the ranged and mages kill Suprana. Once dead, they assist me in killing what's left of Chirada. Then we wait for jump kill spiny and hide. Pretty much rinse and repeat.

With this strat we win all the time. As I am killing the other sister, I never have to be next to Garuda beating on her unless she is in the middle. Overall this strategy is safe and works like a charm