Hello, I am Kamihime player. This is my guide.
I don't recommend multiple element unless you have a lot of time and elixir.
Soul:
Main soul:
- Andromeda: For survival (Recommend for new players)
- Siegfried: High damage when the boss is stunned (Should use while "Burst Time" is active)
- Arthur: ATK up(++), Miracle Chalice (Can use "Full burst" early)
Extra skill:
- Gawain: DEF down(++)
- D'Artagnan: ATK down(+) DEF down(+) and "Snatch" (if you like)
- Mordred: "Black Propaganda" is helpful for a long hard fight
Kamihime: use only one element each Party
Weapon:
+Same element as kamihime
+Many "ATK weapons" as you can as long as you can survive (Boss can deal more than 8000 damage).
Single element:
+During the event, focus on SSR weapons if it is your element. If not, then focus on Eidolon.
+If you use only one element then you really don't need to spend a lot of money or time because you can use all material to upgrade your only one element.
+When you have completely upgraded your element, you can upgrade other element.
Example: Single element (water)
Thunder boss:
Ragnarok: