Wilma can turn into a ghost at will as part of her Astral powers, and with this ability she likes to scare people around Halloween. Moving objects, making ominous sounds and shadowy figures, touching people with nothing there, Floating orbs of light, all the usual spooky Ghost stuff.
Don't worry though, she's a fully sentient spirit and doesn't mean harm.
She can also use this ability for spying, turning invisible and silent to observe from the Astral plane. She can also "Posess" a willing partner and pass on information and visions she's gathered.