I was thinking it would be cool to make a character who only uses archery and destruction runes to do damage. Are they effective? Are they effective even at high levels? How much magicka do they cost? What perks do you need to reduce the cost?

Thank you from the deepest corner of my skooma filled heart.

Yeah it is fun shooting something with a bow for them to helplessly trip a rune. They are pretty effective if you get the augmented flames etc. perks. On higher levels you can use them in conjunction with the wall spells to deal good damage. Using runes alone at high levels i don't know...

Oh, you only need apprentice destruction to reduce the cost, i not sure on how much they cost specifically though

What is a wall spell? I haven't really bothered with destruction very much because of its problems. How much magicka do you need? What level spell is it?