Second, I really wanted to play in the frost talent tree. First: When I first created my Embermage, I was going to be playing him mainly solo as I had plans to play other classes online with friends. I started going with this build for 2 main reasons.
This has simply worked for me for the first 2 Acts of the game so far. Remember, a caster is still a caster and is in no way the equal of what the Engineer tank can be. The general outline for this build is to fill the roles of both a 'tank' as well as the AoE ranged 'mage'. Below is a general outline until I refine it over the course of the game.
Currently I am just finishing with Act 2 and so far the build I have been doing has been working well. *This is a guide I will be working on developing as I continue to play through the Acts of Torchlight 2.