Love the cover art, and the innovative way to use an ability score as the range of a roll-over *and* roll-under system (ala Lasers & Feelings, but with a D20 roll, and limited to the limit of CON).
Giving a player a lot of freedom to decide what *kind* of necromancer they are.
Also, the CON casting feels very authentic, I don't think I've ever seen a good implementation of CON casting before, but this really works great.

I love the idea of ommiting souls and using the concept of nerve bundles in it's typical archetypical place. 

10/10 would recommend (and use for my own games).