Well then, changing my vote.
[X] [Split]
-[X] Have Circe, Archer, Medusa and Shadow Servants engage Brihannala.
-[X] Have Shielder, Luke, and Mordred engage Cu Chulainn, with Medea acting as support. Ayako switchs between support with Medea, and getting in close when she has the opportunity.
--[X] Make a copy of that bow Circe showed you, and pass it to Ayako. Ruby is powerful, but having something she's more familiar with on hand could help.
-[X] Have Illya, Shirou, and Ritsuka stay back, survey the battle, and take potshots.
Commenting on the story, I'm surprised Ayako is able to do so much to Ruby. Going by the gauze she's still talking shit, but she still hasn't tried wacking Ayako's mind directly again. Either Circe had a really good trick to get her under control, or Ayako was even more persuasive than I imagined on establishing the pecking order around Shirou. (Ruby's on the fucking bottom and it's only because of Ayako she gets to be around him at all.)