So I'm here to drop some REAL advice, stuff that I didn't see for far too long that people should've been told from the beginning. I've been dabbling in the endgame which at this point is spiral abyss, the hardest content. Some of you who haven't messed with it much may have heard you need TWO main characters for it and that much is true, but there is more to it. You need two main DPS, and I'd also say you need two healers. You alternate between teams in Spiral Abyss, which means you should also have TWO claymore users, because claymores counter a lot of annoying shit like shields and geo. If you can, I'd recommend having your two mainly-invested characters be damage dealing claymore users, but that isn't strictly necessary.
So optimally your two spiral abyss teams should look something like this Main DPS(Gets all the investment, both of them), Healer, Bow user and either a support or a claymore user that can function as a support if the main DPS for that team doesn't use one. That should make it a bit easier than having to figure things out for yourself, and might save you a lot of mora on leveling characters/artifacts/weapons. You don't necessarily need a bow user if you have a spellcaster but they're pretty much strictly better for dealing with most ranged enemies like a flying ruin hunter.
My current teams are as such
Team 1: Diluc(main investment), Barbara(heals), Xianling(support/double fire buff from Diluc, and either Noelle or Sucrose depending on what I feel is better.
Team 2: Keqing(main investment), Qiqi(heals), Fischl(bow/support, Noelle or Beidou depending on what I need.
I've managed to get pretty far, and that's by pretty much entirely investing in Diluc and Keqing, with a bit in the healers too because things start to really hit hard in higher abyss. I'm lacking a second bow user at the moment so I've invested in Barbara's damage just enough to cover such bases. Mostly though you want to prioritize your two team leaders, then the healers.
