In the rules it says that magical powers only need line of sight. Does this mean the sorcerous blast can be cast from behind your own troops (even without being in base contact like shooting)?

Yes. There are no In the Way rolls for magical powers.

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http://napoleonicstrategybattlegame.yolasite.com/

Yes, magic is treated differently from shooting .

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Backlog:
21/01/2015: still 319 Models to paint or 27,01%
30/12/2016: Somehow the backlog has risen up to 900+ models :/

Nice! I am going to have some fun with Saruman the Wise and his 4+ casting plus re rolls