You know now you will have to write up a battle report or two to show how this stuff works out for you.
I think the conceal primaris is probably the best power for artillery as you will be nearly invincible against shooting in any ruin/area terrain.
You may want to think about replacing the warlock with a farseer, you can use the extra 30 pts you found + drop a scorpion or something. This will give you prescience + guide + perhaps screech or other power. The guides will help your fireprisms and battery while sreech could be very useful against assault units.