Shamans count as clerical spellcasters and follow a god. If they follow your god, they are peaceful. Killing them will anger their god.

If cauldrons are added, new special room that contains several gnomish wizards, orc shamans, and kobold shamans standing around a cauldron.

Assuming monster casting has been expanded somehow to include ally buffing: an orc shaman can generate with a group of other orcs.

In Orcish Town, there should be a powered-up hostile orc shaman who has taken over from the dead Minetown priest. Possibly it could even have an epri struct attached so that it tends the altar. If you pacify it, you can donate to it as you would a normal temple priest.