Ok so I have a level 20 mage and would really just like some help with stats skills and rotation.

I'm looking to have a class that can solo pretty much anything and can nuke like a logo.
I currently have all my points into int and as far as skills go I have max heal max lightning. I have one into fireblast or whatever it is. I think o have 5 into weakness however I don't use it that often. It doesn't seem to work well. What I normally do is run in to a big group cast lightning fireblast then heal. I'll run around and continue that rotation until everything is dead. However sometimes there are to many and the damage is too much and I end up spamming heal and potions. Now I'm just babbling but basically I want to know if there's a way to make a mage that can run into those groups and just demolish everything. So...any tips that would help me make this type of character?