I honestly see no reason for it to be different from the Finger of God. 100 a time, makes sense to me. The only person that an ever increasing price (for anything) makes sense to, is 22Cans accountant ;)

I would like it to be a per second cost and the ability to drag across a whole landscape and have trees spring forth.

I could see a rising cost if the spell worked like the "magic forest" miracle in Black & White, but one tree at a time, with costs quickly rising to the thousands for the small benefit trees provide is indeed, ridiculous. This is one of the two things about Godus I find absolutely stupid. like, can't even ride the shortbus stupid. the other being the difficulty in creating a new world. shouldn't that be an option on the main screen, like every game that isn't Godus does? ah, but that rant is for another time, another place.

That rant has been a regular one. Godus is "supposed" to be a one shot play through game. I've no idea why. Espically with threats like the Astari where you can fairly obviously lose. Oh wait.. Just buy more gems!