She's good!
Skill 1: -ATK+DEF down (B frame -20%) to ALL enemies. (7T CD, 180 sec)
Skill 2: Applies water attribute buff to self (50%) (4T CD, 2TD)
Skill 3: Applies triple ATK guaranteed to self/ Burst gauge increase rate DOWN (8T CD/ 3TD)
Assist: Attacks ALL enemies at once on normal attacks. (Awesome!! The same as Christmas Volos!)
She'd work well with Aphrodite, I suppose, as Aphro can cleanse her stupid self debuff. Or anyone else that cleanses.
Though, with that really nice attribute buff, the triple attacks from Cybele will be super strong. Not to mention that it attacks all enemies at once.
Burst gauge decreasing rate drops by x10, so after a triple attack, she'll gain 3 burst gauge. (Correct me if I'm wrong?)
But it's worth pulling for her, since Levi comes out too. It's always nice to have a must get SSR Eidolon and a L/E SSR hime in the same rate up gachas. Good luck on getting one or the other! (or both!)