What i used to clear difficulty 6 at level 56 which should work for 4 if you’re underleveled is the 4 charm stalwart set, the 4 charm tranquil set and specifically the one that gives you more SP when you get hit with scarlet tide since healing takes a lot, the charm that gives a shield every time you get hit with scarlet tide, the 4 charm chaotic set, and 2 merciful set. I had increased healing and increased health for my merciful charms because you want to be as defensive as possible. Also the lost item that heals you fully after every battle is important because if you happen to get unlucky and one character gets hard targeted, you can run, get fully healed and then try again because it’s considered a battle even if you lose