This boss has to much life for crit teams. It always skills on 3rd turn and kill every offensive girls. It has precision buff and make Evasion useless after 3 turns. The best way to deal with it is defensive teams with a LOT of def buff. And counters. After a while, it seems it don't use skill anymore. And you can kill it with grils with HP drain and enough def to kill it. Kerria can be good for that. Pink Miko too after promotion and teamed with Counter+Crit girls.
I'm pretty sure you just can't win with 4 Crit teams. Like Earthworm's phase 1 is designed to rape defensive teams, this one is designed to be very strong against the best team achetype in the game. HP drain+Def buff is the key of victory guys.