Vervain, Cattleya, Cowslip Maid, and whatever else you got that increases skill damage and skill act for castle. I use Reeves Spirea (Easter) and Edelweiss (New Year) which both are excellent for this purpose and have heal as well. When not playing castle, I am using Azalea in place of Cowtits. but for the castle you need negate. My resources will be going to this team for quite awhile.
Edit
Dont forget the FMs!
Until I get my skill act up, Im using 1.5 first turn on Vervain so her effect starts. Else use Skill act boosts for Cattleya on all.