A Little suggestion would be to get Dodge Attacks and Heat Sheild very soon. This will likely double your defences. I would personally put some points into earth mastery itself to get more health and dexterity and also bring out the coredweller. Beside that your build is ok. My build would look like:
Battlemage build
Your damage though is horrible, sorry. Find some green axes or clubs in shops and put some attack speed or % damage relics in them. Also look for green fire boosting weapons, since you are a battlemage. You can always try them on and if they do not raise your damage, sell them back without loosing money. Just as an example, my level 8 assassin deals 243 in dps at spartan war camp normal, no cheats or twinking except 2 achilles relics in 2 green swords. So i would say that your damage at a minimum should be 500-800 on start of Epic. I know this aint easy since Battlemages aren't good damage dealers, compared to other builds.
A battlemage gains very little fire damage from earth enchanment. 85% fire damage and 5-8 burn damage over 3.0 seconds and 21% damage and 98 burn damage over 3.0 seconds is still only 35 extra burn damage in dps, since % fire damage do not boost burn damage. Monster has fire resistance aswell so this number if likely a lot lower. Without fire dealing weapons you get 0 extra damage from % fire damage, so unless you have weapons with high flat fire damage, Earth Enchantment is totally worthless. Just 1 point it to get Brimstone.
Purples can drop as soon as Helos in Epic, but never in normal. Just move on to next difficulty and go farm Nessus outside Spartan war camp. If you do it a few times you should have a good chance of getting some purples.