Thread: Noob Question

Yamaraja and Mordred are both B frame, they don't stack

I would go Joan of Arc first I believe, overall good skillset and Trial by Jury is especially valuable considering the rest of the team

if it's normal amon, then she isn't needed as long as you have enma (yama) as she also have block debuff.
mordred can do a lot of debuff so it'll get enma's 3rd skill stronger, but as said the attack and def debuff are the same.
again, as sais above arc is good with her cut damage and attack debuff, you can also use ambush as extra skill for another def debuff.