Element based core kamis are nothing compared to 100% eidolon. Sol is the only one, by which you won't make any mistake, as long as you don't have her
![Roll Eyes (Sarcastic)](https://harem-battle.club/images/smilies/rolleyes.png)
She is useful for all elements.
Andromeda is shit. Her revival is almost useless, because the boss deals aoe damage and kill 2-3 kamis at once, even damage cut is better than revival. Take this event as example, I use Cassiopeia instead of Andro only because of chaos magic. If I had sol, I can forget about cassi and use mordred or whatever, which give more damage output and boss control, and it doesn't matter, which element I'm running.