Mordred sniper shot/ D'Art black propaganda SSR Nike Sol Raphael (so max atk debuff I think?) with Ouroboros Echidna for the extra blind and dizzy, especially if not using Mordred. My 5th character slot goes to Ea for damage, and mostly because I just ran out of SSR hime to work with, and I don't really have good SR light/ water hime at the moment, save for a Triton I'm still levelling.
Edit: I realise from reading the JP wiki that I should really start working on a damage build... some of the quests (like rank 5 accessory) seem to work on a kill or be killed basis, regardless of how tanky my team could possibly be lol.