Just got past Nurse Call.... Hoooooh, boy, that's what I call a difficulty spike from the main game
Used Margaret Covenant, started battle with Andor sword +5, then mainly Divine Punishment (the mace, 50% regen is insanely useful), 2-face shield, sky knight hat, sailor clothes, then 1xblack rabbit ring, empty ring +3, ring of my struggle, resurrectionst's ring.
Started with indignation (from the anchor), rot (from the Gla'akid) and then spam black slash (4 strong unavoidable hits, no CD, shit's broken as hell). Just keep health up and dispel buffs (with the technique, or with Mary's wand, whichever), refresh indignation and buffs, and apply requiem once the other soldiers appear. If health gets too low use Catherine's wheels (my personal favourite, 4x 2 hp-drain-hits with bleeding-chance), always after dispelling eventual buffs. Focus on murdering Nurse call, then clean up.
Applying the extra-turns buff to yourself is really helpful, since it seems to count towards cooldowns (definitely didn't have to wait 8 turns to re-use the wheels), while it doesn't affect the buff time.