Astro-projection is where a person can have something similar to an out of body experience where a ghost like form of them seperates from their body. Rending their real body useless or active, the ghost form is controlled by the person and can phase through things. Sometimes, phasing though living beings can be harzardous to the victim. One of my original characters has this powers, but I'm not sure whether I'm going to use him for the game or not....
The results can vary upon the ghost form phasing into or through someone. If into someone, then (in some versions) the ghost form can take over and poesess the body they take. After they are done, the ghost can simply phase out and return to the body. Yeah, difficult to defeat someone like this. That's why I love this character whom I call 'Nightmare'! But, he won't appear until I have the original stories or so ready to add him in.