the way i see it, if you have gaia, you don't need Sol... if you're that worried about survival and have gaia, use a gaia/joan combo and practically say "fuck all" to damage... along with being able to alternate between two regens which should cover healing...

but since fire is the advantage in this event, you're gonna want to just go all out damage anyway. dark is the only issue as it lacks healers, but if you got a decent amount of atk/def down, then you should survive with just andromeda (or cassiopeia since the boss can buff herself) if you really need to heal. Bonus points if your dark team has Osiris like me, cause there's healing plus potential damage.

but if your grid isn't up to snuff, then you probably shouldn't try the solo challenge anyway. besides, it's just extra tickets... it's not something highly valuable like drag eye shards, it's just something to slightly help mitigate the grind (cause getting SSR and even SR pulls is a major pain in the ass).

Sol is stupidly strong, there's no denying it. but Ikki is right in the fact that you shouldn't be reliant on her... Despite her powerful kit, she's still oriented to light, meaning you lose damage if she's not on that team and you're using her.