It so happened that the ruins where I executed the Thalmor convict stood over an underground castle. A haunted one with a friendly ghost, Ilfhild Merilion (not Casper). She informed me the dead stirred once more at Death Mountain so I raced back there and took the first available companion I could find in the local inn, a warrior named Tenshi.
And then... the draugr invasion began! This is nowhere near as scary as it should have been though, mainly because of where I was. As soon as the ever growing horde would spawn, all the daedric guards and dragons would leap into action. I just took a back seat during the whole thing and enjoyed the fireworks!
Those flames are so pretty!
Eventually all ten waves of zombies were slain without my active participation, and there was only one friendly lost in the whole thing: Tenshi, who got Fus Ro Dah-ed by a draugr deathlord off the side of the flying mountain. It was ridiculous but very entertaining.