MY PERSONAL OPINION
As others have said she is weak since healing doesn’t effect ghost form and buffs don’t effect her.
Items don’t effect her in ghost form but she can trigger them. But too low defense & HP for revive scrolls.
I didn’t really see her usefulness for Titans until we fought reflect red rare titan 6* Ancient tiger with special skill Sable slasher ( damage all enemies, debuff all enemies mana generation, reflect all color damage ). Where my team was dying in droves even with two 42% Healers and two dispellers since no battle item removes enemy reflect all color damage buff.
She appears to be designed to take out 4* reflect damage/ counter act enemies like Boril, Sumitomo ( she is weak against Cyprian ).
She would be more useful if she was Red/ Green/ Blue since reflect purple challenge event Pirates is also her weak color. This may be on purpose, or by chance, to keep her from being over powered.