Alright bear with me here. I am only a level 10 Mage as I began this character on Saturday so I am pretty weak. My only powerful spells are my fire Atronach and my Firebolt. Those are useless against the Ash Spawn and my others are not effective either. Also I am a very unpracticed Mage as this is my first magic wielder ever. Some help please.
Welcome to the Dragonborn DLC, a land of getting one shot by Netch's and bent over by Ash Spawn. Wait till you start running into Lurkers and you will be weeping all the way back to skyrim to get your baa-baa and cuddle with your mommy.
On a serious note go back to skrim till you get your destruction and conjuration arsenal a little more matured and you have a big enough magicka pool to summon a hit sponge and still cast off some spells.
Secondly go to Tel Mythryn and do the quest their to unlock some very powerful destruction spells. Once you get Whirlwind Cloak you are set to go and fight any enemy you want.