i went with the death strategy featuring Vanille as leader.
Death has a low chance doing insta kill, (15%) but this gets higher if you use vanille's malboro staff(improved debuf).
This tatcic involves luck but is the easiest way, my reccomended setup:
Vannille/Hope/Lightning
Sab/Med/Med<-- start in bthis one.
Sen/sen/sen
Rav/rav/Com
as mentioned in the post; go to sentinel only if screech is used, otherwise stay in the first paradigm and keep casting death manually. use the third paradigmn to kill the other mobs Good luck ;)