With 3.0 we have a new mechanic where we drag thralls to an altar to sacrifice them for evil sorcery purposes. Why not have this mechanic for some of the religions? How satisfying would it be to sacrifice a heart to Set on the altar’s stone table? Or to toss a screaming victim into the pit of Yog? I’m sure there’s something PG13 you can do for Derketo on that slab. Maybe have them wither away like when you steal a thrall’s soul.
Obviously this doesn’t work with all the gods. I don’t think Mitra would take kindly to you bludgeoning someone to death at his feet with an ankh, but I think it would add some flavor to the more evil religions. It’s also not as efficient as going into a camp and hacking religious items out of corpses, so maybe a single sacrifice offers a higher output of rewards.