Tyro - SLG, Yshtola - Stoneskin2, RedXIII - Lunatic High, Bartz - Lupine Barrage, Ashe - dont matter.
RW - can use SG/SS2 if have Lunatic High or vice versa. This setup dont need RW (ive been using advance, hote, planect protector and also won without using any RW).
Can drop wrath to slowga if trying master.
Im not sure how well it would go without wall/hastega/AoE cure, probably would drop RedXIII for another healer with protecga + haste and bring RW wall.
Last phase trick is to have a backrow char full turtle and defending, and the other healer curing him so Vossler will always target him with triple/quadstrike (it sould do ~400x4 with wall, protectga, steal power, full break and defend).
Ashes Ruinga deals over 8000 in everyone with this setup and she beats both adds. Currently, im using Bartz and Tyro to clear adds faster then sleashing SB against Vossler.