How quick do the rune spells become weak and pointless? I'm looking forward to getting these spells but I don't want to have to stop using them in the future because they get too weak.

thought id share this.
http://www.skyrimnexus.com/downloads/file.php?id=178

I used them until I got the wall of flames spell.

where did you get Wall of flames?

Faralda, College of Winterhold (Hall of Countenance)

I think you need a high destruction skill before it becomes available though. Mine was 60 something at the time.

Thank you.