I set the ghosts collisions so that they only block physics bodies and the parts of the world, allowing them to have solid collision with the ground, walls, and rocks, et al. I had trouble getting ghosts to ignore thrown rocks, so the rocks had just been bouncing off ghosts when being thrown at other players. I changed throwable objects so that they would ignore the ghosts as soon as they left the players’ hold. This meant that the ghosts did not block the thrown rocks, but the ghosts were still intangible to the rocks after the rocks had landed. I finally added a node in the rocks that block the ghosts again after they hit something, meaning the ghosts can act on the rocks again.