According to Bolg, no.
But casting INTO close combat sounds cheesy to me, fluff-wise at the very least. You're not supposed to be able to shoot into
cc for fear of hitting your own guys, but space-magic cleansing flame that hits EVERYTHING within 9" is safe?
I guess I could allow it since getting that close AND having another unit in
cc would take at least some minor maneuvering skills.
Automatically Appended Next Post: Just looked up Nova in the
BRB. Maybe shoulda done that first.
Firstly, under Witchfire:
a Psyker must be able to see the target unit and cannot be locked in combat if he wishes to manifest a witchfire power.
So that should satisfy the
OP.
As for casting INTO
cc, just for completeness sake:
a nova power automatically targets and hits all enemy units within the power's max range, regardless of line of sight, being locked in combat, intervening models/terrain and so on.