You can summon demons to perform actions or grant you special favors:
summon demon [soulstone] detection summon demon [soulstone] protection summon demon [soulstone] spellcomp summon demon [soulstone] alchemist summon demon [soulstone] power summon demon [soulstone] corpseretrieval
Detection grants you a full complement of detection spells.
Protection grants you a full complement of protection spells.
Spellcomp summons a demon willing to provide off-world spell components.
Alchemist summons a demon from the demonic brewing guild, which provides reliable potion services to many creatures on many planes.
Power grants you an extreme amount of magical power for a short time.
Corpseretrieval petitions a demon to find and return your corpse providing it is on the same plane.
There are a couple of exceptions to this demons will refuse to retrieve corpses from the angelic planes but will always be willing to gather them from the demon realms.
You may only ask for such favors occasionally, and in each case a fairly powerful soulstone will be required as payment.
