I've been thinking what kind of core would ghostbatman have ?
What if he had a light core.
Because irony, also a way he could use it without knowing would be absorbing light to power himself.
He disappears into shadows. Rooms darken when he enters them.
Bruce being dragged outside in the day by a loved one for his mental health and being amazed how much it helps.
Bruce and Clark sunbathing together.
After he learners to use his core on purpose he creates lights for kids who are scared of the dark and people he rescues discover the path home is alot easier to see.
Bounding with Duke over both having light powers.
Light in darkness as metaphor that he is more than his depression and the tragedy that surrounds him. That he is ironically a source of light and hope for the world.
Batman as the moon.