Since i recently defeated Rania and there are no tips around i'll be posting my setup and strategy.
Erica got the full tfs treatment. So no deathmist core. The battle was fought already transformed with all members at +8 attraction or more. Natalie was the partner.
Equipment: Illusion Core for mdf buff given to Erica. (Lovely barricade from Granak fight works too) Bee core to debuff enemy given to Natalie. Slime queens core to act as a second healer given to Veronica. Insanity core to cure charm given to alice together with the cursed doll for charm immunity.
Instant death resistant panties given to Erica and the corset given to Natalie.
Everything else should be focused on mdf. That way you'll only occasionally need to revive someone. The water witch merchant sells an enticing hairpin which i gave to Erica but it could've done without.
Erica will act as the mana and tp supplier. Allowing the others to constantly attack without taking turns using items. Every 5 turns apply the mdf buff and keep the mp from everyone above 20.
Natalie will be debuffing healing and attacking. Make sure to not waste time using items with Natalie
Veronica will be attacking most of the time. If either Natalie or Erica run low on mp make sure to use items with Veronica or heal with her instead.
Alice will cure charm and deal damage. Once the bats were gone i started using wraith shield.
I didnt take any effort in maximizing damage. You'll mostly be occupied keeping up your mana usage and healing most of the time. Its best to take your time taking out the bats first and afterwards do at least 100 damage every turn. This way you should eventually win. Good luck!