ok I have a High elf with 500 mana Destruction maxed out Inteligence maxed out. My question is this could it or is it possible to use fingers of the mountain at max level? If so how can I do this right now it's gonna cost 710mana to use it with everything maxed out and I have a high elf with atronarch and mage. I have tried this a few different ways only way I can think of is to fortify my magic with multiple potions but whats the point to only cast it once.

Fingers of the Mountain is a crap spell. If you check the UESP, it costs more than a spell of the exact same stats would if you custom made it. http://www.uesp.net/wiki/Oblivion:Leveled_Spells#Finger_of_the_Mountain

So cast something else.

Seriously, Fingers of the Mountain is a terribly inefficient spell. You should be able to create a custom shock spell that uses a lot less magicka.

I think the inefficiency is a built-in punishment for disloyalty to the Mages Guild.

thanx I created a custom fire spell that does 100 points of fire damage on touch for 4 seconds and it only cost me a little over 100 mana much lower than 710 for 200 points on target for 2 seconds like fingers of the mountain.

I've always suspected just that. The only way to get it is to betray Teekeeus (even though you can sort of make it up to him later), so I tend to think that it looks really impressive but is actually really badly broken just as a sort of object lesson.

The Fingers of the Mountain is a spell that bypasses Resistances, and can be a very effective means of crowd control when used on large groups, but it is a magicka hog.

Good to know I'm not missing anything by turning down the offer to steal the book. I just think she's a [censored] and doesn't deserve to have me help her.

In the CS, Fingers of the Mountain is not designated to use the same default auto-calculate spell consumption option, like most other spells.

How would I fortify my magic from 500mana to 710 so I could cast the spell if I wanted to use it?

Having a restoration skill of 100 will help.
If you have access to a spellmaking alter and a fortify magic spell in your tombe (that you can cast), make several of your own fortify magikca spells, each with a different name. Then cast one after the other to spell stack them.
I've tried it before, but not worth it IMO.