Ohh..What type of descruction would be best? Fire? Ice?
Fire does the most damage, but dunmer are 50% resistant to it so those battles will be twice as hard.
Frost is great because it slows people down and takes their stamina at the same time, but there are more nords than melee in this game who have 50% resist to it as well.
Lightning though, moves the fastest, does great damage, depletes enemy magika, AND no race in the game has resist to it (besides breton with their 25% resist all magic).
Illusion is good, but it doesn't work on undead, daedra or machines until you get it to 100 so the main quest line will be annoying with it half the time (lots of undead and machines, but mostly undead). Conjuration is great for raising allies, you will be more of a deathknight using this though. IMO use conjur battle axe in right hand and raise zombie in left hand... use the axe to kill someone, sheath, raise as ally, then resummon the axe. If you want to use actual spells and defend against spells aswell, try destruction and alteration together. Put your favorite kind of weapon in your right hand and your ward in your left. The ward will deflect both magic and melee damage when up, depending on how far away they are you can switch to spell in right hand and ward in left or ward/sword OR destruction spell/sword for extra damage.