Yeah, it's best used for siege warfare.
But man, it always feels good to get that first shot off and do 50 - 60 points of damage on average and the victim (if he survives) still has to save vs. death or die of massive damage.
Plus, the area of effect is a 20' diameter circle, so you can take out a LOT of bad guys with one hit!
I always hated the 1 turn casting time, and since priests get so few really powerful low level spells (compare to wizards - fireball, lightning bolt, etc.), I changed it to 1 round casting time. If you think about it, the only spells with any real "ooomph!" that priests get from 1st - 7th level spells are:
Call lightning (3rd)
Flame strike (5th)
Blade barrier (6th)
Creeping doom (7th)
Firestorm (sort of) (7th)
You don't get flame strike till 9th level, blade barrier at 11th level, and creeping doom or firestorm until 14th level. So I made casting times for call lighting to 1 round, not 1 turn.
I know priests are mainly for supportive and bolstering roles, not as the main cannons of the team, but still - they should have SOME decent bad as spells at lower level as wizards do: