So, there's this quest, "The Man Who Cried Wolf" in vanilla Skyrim, where a bunch of Necromancers are trying to summon... .

Now, in Wolfskull Cave, where the quest takes place, there's a bunch of swirly purple magic effects flying around (you can see them http://www.uesp.net/wiki/File:SR-quest-The_Man_Who_Cried_Wolf.jpg). I want to use those effects in a quest of my own, the only problem is, I can't figure out what causes them. I've looked around Wolfskull Cave, and I just can't figure it out, since they don't actually render visibly in the CK.

The circular, purple light that the magic swirls towards is there, but I can't work out what's actually causing the magic effects themselves. Is it a spell? An activator? A moveable static?

Can anybody do a little sleuthing and help me figure it out?