I too have suffered from the bad back syndrome. Whether I am storytelling or playing, I will get up and walk around the room, still doing whatever role I am in. I will take my character sheet or initiative board with me and look at the board and make calls based on what I see. Sometimes it helps the story along to see different angles as well as my back. I plan on going out with dice in my hands and surrounded by friends. I am sure that is a plan for all of us.
Purge Spirit is a winner. "This spell affects astrally projected creatures, ethereal creatures, haunts, incorporeal creatures, mediums channeling a spirit, and phantoms, and at the GM’s discretion can affect other spirits or creatures made of ectoplasm.
Incorporeal creatures take full damage from purge spirit."