Alright, so I am on the boss battle for Aryth's Spire where you verse Aryth, and I read in the guide that if you defeat the middle one that you will automatically win and not have to defeat the other two, but that didn't happen for me? Can anyone help?

That happened for me too, I think the real Aryth is different every time. Just keep trying and youll get the right one.

I have been trying several times and having difficulties defeating even one Aryth. Do you have any suggestions on a battle party build?

i can give you some tips on your party ^^

well, since you have a bunch of pets for each element (pretty smart, actually), i would usually suggest shadow first, light second, then wind. but for this battle you may want to use fire instead of wind because it deals multiple target damage. Shadow because it deals great damage and also heals itself, and light so that it can heal the whole party. put all proficiency points into health for now. As for equipment, try getting legendary or above. For shadow and light, get illusionist and/or arcanist equipment. For Wind, get myrimdon or ravager, and physical damage, and for fire, get evoker.

for the battle you would want to stock up on exlirs too. hope this helps!