What heroes do you have? Also just beating it or do you need/want to 3 star it?
Best female frontline tanks: Mirielle, Tareth, Driller (requires you have to 1 more frontline hero)
Best female damage dealers: Sylphi, Osiris, Nilya, Serafine
Best female utility (max 1 per team): Jasmine, Lingling, Li Twins
Best strat is to just overrun them with damage so you dont need healer. A team consisting of (random tank from list above) and then the 4 caster girls completely destroys ride of ther valkeries. (If ofcourse their gear is reasonably up to date and they have 5 stars)