1. Mages are a support character that are not meant to be huge damage dealers or tanks.
2. Even though they are support, drain deals the most damage of any skill, and fire I believe is second or third.
3. With this said mages can still beat any class 1v1, the only one they have trouble against is bird and sometimes rhino. And if ms is timed correctly a mage will kill a bird 9/10 times.

So, it seems that you need to change your playstyle, if you try to nuke a bird you will die, which is why you will need to kite.