A question about ghosts:
Incorporeal characters can only be harmed by force effects or other non-physical attacks.
1. Is this a one-way street, or has an incorporeal character a similar restriction with his own attacks?
2. What would you count as non-physical attacks? Fire? Sonic? Divine? Electrical? Explosive?
That would mostly be setting specific. I have a setting where focusing your inner spirit (call it chi for want of a better word) allows you to use weapons to damage spirits (at half normal). For that matter you can make an "unarmed" attack with just your chi to do the same. I can see fire for corrupted incoporeal things. And possibly sound for certain undead. Divine should just work because ... divine. The others seem like physical damage to me. (Sonic too unless there is something else going on there besides just sound.