Great interpretation of the theme. The balancing act between using the necromancer's near-invincibility and offensive power and the dark spirit's vulnerability and enhanced movement is really cool.
My only annoyance with it (could be because I was playing on keyboard), was that when you enter dark spirit, the spirit faces right and moves in that direction. Probably because the spirit is always moving. It tripped me up on the boss a few times.
Visuals are amazing as always. Sound is fitting. Lots of gamefeel. Amazing work!