"Evlin" spell - how does it work?

[BB Shockwave]

There is a new chaos magic spell (I have not found it yet, just seen it in the manual) that conjures an "Evlin" (dark evil matter looking like a cloud). According to the description, the Evlin flows inside a neighbouring unit and (Like Reaper's Sould drain) kills 20-30-40% of the unit. It also says something about healing undead...

My question is, how far can the evlins move - just one cell? - do they attack your troops as well, and do they resurrect undead (even enemy undead?)