In this setting, undeath is not a given. While there has been some theoretical conversation about it on paper, there has never really been a practical application of it and undeath is considered a festering wound upon the world. It is unnatural. Because of this magics such as necromancy are not fields of study and do not exist at this time.
Undead Information
Wherever there is undead, Nerull is nearby whether by chant or by energy. It is thought that this is all connected to the dead god. Nerull is the reason that undead cannot be controlled: he takes control of them and overrides mortal methods of restraint.
Dia explained that the best way to deal with the undead is with holy fire or holy light.
Ilxavar also mentioned that there are old parts of the Goblin Empire that would need to be reactivated with the looming threat of undeath.
Undead Sightings
Casting detection poison & disease on the corrupted wine had Dia realize that there was a deep chanting of the name Nerull.
There were two explosions (one directly on Dia) that had necrotic energy on them and required necrotic energy to be purged and cleansed to fully receive healing magic.
Edruch has the bog mummies in the basement of his museum of cultural studies that he was attempting to extract information from on orcish history and culture.
In the city of Amoth Bridge we found the corpses of ghouls in the epicenter of the explosion.