Looks like a copy of the lightning mote attack that adepts and swamp hags use. If it hits, you eat a damage flare.

AIM: GS4Menos

>Here lies the formless world we´re living in
>Gravity is finally giving in
>High altitudes and still upward we go
>I was never meant to lead but to follow

Yes, yes it does hurt. Don't forget to pawn those hammers...

http://www.krakiipedia.org/wiki/Decaying_Citadel_guardsman

Not sure if swamp hags do that attack. Far as I know, it's an ambient affect in Oteska's Haven, like this:

The stink of sulphur seems to drift down from the fog overhead. A moment later the fog is illuminated by slow moving, blue-tinted arcs of lightning. A muted sizzling sound crackles overhead.
A narrow finger of blue-tinted lightning streaks out of the fog, striking your steel flail! The air crackles and pops. Bright spots dance before your eyes. The stink of sulphur is intense.
The lightning snaps your right arm!

---

>An officer of the Sorcerer Guild arrives and glances around. "Ah, there you are, Vathon!" he says in a slightly agitated tone. "I have come to formally declare that your membership privileges have been revoked."