Rekt^
& I agree with uber however, optimal build at 18 would be 5 heal 1 icestorm 6 light 3 fire 1 drain 1 frost

if you wanted to incorperate ms, I'd advise you go 52 int, rest dex. This enables insane regen, heal, tank & allows the use of fbows to nuke if need be.
the build of that would be 3 heal 5 fire & repeat the rest of my build I said above^

check out my guide for tips & gear at 15-19 mage.