Yes, you are right: spells which target the caster affect the slaves too. I do not recall if Immolation worked at all, but it might be worth trying... Especially if coupled with Phoenix Pyre (if *that* works, that is
)! Hmm, you could get rid of fatique by Earthpower, Earth blessing and Relief... Pity the Relief-caster will probably start casting Barkskins/Protections.
Not sure about the sword, I would gave saud that only the fire damage is considered magic but it doesn't seem to work with the answers of this thread... Good point with that.