I haven't found anything in game that says what these phenomena are although they clearly seem to be Falspawn related like Falmorphers and the Bayze. If I had to guess, Vizbolts seem to be the result of the F-Factor corrupting the atmosphere but what about Gehl Bulfs? Are they some out -of-phase type of Falspawn? Why do they only have a limited time of activity and why doesn't a Dark Falz like [Apprentice] try to make more frequent use of them?

I'd like to know the same thing, I can't find ANY info anywhere about gehl bulfs and what they are.

@RedDingo7777 said in Lorewise: What are Vizbolts and Gehl Bulfs?:

Are they some out -of-phase type of Falspawn?

They're actually a mobile variation of those spheres that sometimes spawn and slowly move about, and take one hit to destroy.

Vizbolts are likely just a An "F-Factor" Burst of a sort (IE: a Dark version of PSE Bursts), where too much Falspawn particles are in the air. Think of it as a lightning storm really. At least that's what I'd probably do as the lore writer of this.