I'm currently playing a level 6 infernal sorcerer through book 2 of Hell's Vengeance. I'm not hugely familiar with a lot of the lore/setting/mechanics (either this campaign or Pathfinder generally) so today I've just been looking ahead at ways to go with the build as I level, researching feats, prestige classes, and other such fun things. I'm thinking of going prestige into Diabolist and take a load of Damnation feats, for flavour.
I came across the spell Create Soul Gem and have been doing a bit of reading on The Soul Trade. It seems to apply exclusively to demons but it got me wondering about devils. Would a contract devil, or other LE outsiders, accept souls of defeated NPCs for trade? Or just as gifts to help gain favours? Would they value them at all?
Are there any other interesting uses of soul gems? I'm intrigued by the idea of taking the souls of all the LG Iomedeans my party will kill along the course of the campaign, and trading them to eternal damnation.
