Fumiko was waiting for someone to speak to her when she heard a strange noise and felt a dimensional disturbance. 
She'd never experienced a boomtube intruding on her space and it startled her. 

So startled was Shadowdancer that she summoned to the edge of the shadows around her army and was ready to release them on this plane. She relaxed a little when she saw the Flash and Batman though Cyborg's condition did key her up a bit.

She watched as Hellfire was administered to for poison by the combined efforts of the Flash an Batman.

Then the Batman explained why the others weren't here and the set about choosing teams and assigning targets. 
"Hellfire, Owlet, Frostbite, Shadowdancer, and Brick" he said putting her on the team attacking the police station. She was to be a distraction and though some small part of her was annoyed she was also excited.
Fumiko felt a thrill at the opportunity for combat, her darker nature would find the release she so craved.

When people saw her as the human Fumiko they were either unaware or forgot that she was also a Queen among Oni, ruler of a plane of shadow. She was not a malevolent Oni but a guardian an Oni still and that made her a lover of combat.