When the sisters spawn, offtank should take the green (seems to always be between garuda and red) to the north while the main tank grabs the red (tanking both garuda and red) in the south. Healers heal from the middle and dps burn down green first. Then kill red. The swap seems to only happen between red and garuda. Next another set of feathers spawn this time with a green "prickly" one I believe. Avoid killing the green one until just before her big aoe as it provides a shield that will protect the party.