Yeah Magic Blast is very powerful! Fire wall too! I combine Mageskills with Ranger (use frequently a bow!) and Warrior, to put a end on the enimies when I have them alsmost killed with magic or my bow! And if enemies surrounded me I take a melee weapon to put an end on all foulish Damned One followers ...
Unarmed expertise is also a funny skill to try !
Next time I begin D II, I would try for a good strong warrior .... look if it is possible..?
But I think a "combination" is always much better because of differnet enemies! Some enemies kill from afar is much better, other enemies (like some mages!) are weaker (less armor than warriors), so I jump to them and kill them with melee attack faster than with bow or magic!
Most of the time I first kill the "warrior - enemies" from afar with bow or magic, except if there is also a "healer"! A healer I try to kill them first! Also the same with a "summoner - enemie" ...
On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin, it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !
Magic Blast is very powerful! Fire wall too! 
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