Great idea, I'll try to rattle some off:
spells:1) Possess-Drive
![E v i l [Evil]](/emoticons/e_v_i_l.gif)
spirits into your target, causing them to commit acts of
![E v i l [Evil]](/emoticons/e_v_i_l.gif)
on all those around them. Higher levels cause longer duration and greater intensity of acts, and can even cause permanent possession of weaker targets.
2) Black Flame-Call forth the mystical black flames. They cause no physical pain, but devour the soul of all it touches. Medium levels and above can harness some of this life energy to heal themselves.
3) Fire Lash-Send whips of flames towards your opponents, simultaneously lacerating their bodies and scorching their flesh.
4) Electrocute-Hold this spell on a target to slowly electrocute them to death. Also known as torture.
/Neutral spells:1) Heal-Use your will to heal physical wounds of your own or others.
2) Blue Bolts-Send forth a bolt mystical flames into your enemies, destroying critical organs, giving them a relatively painless death. Only with skilled precision, of course.
3) Sonic Boom-Deafen your opponents (stun); higher levels can shatter bones.
4) Kiss of Ice-Flush chilling air at your targets, slowing them significantly. Higher levels can freeze them completely (would be frozen stiff, and yes, can be shattered).
As far as possession goes, lets say you cast it on a villager in the middle of town. If you're a low level, the spirits would only have a doorway opened so wide (for an out-of-game explanation, that is), so they'd only be able to do so much. You may see that villager smacking someone or shouting curses.
Higher levels make the door wider, so they would essentially go apeshit. Smash windows, attempt murder (strangling maybe?), scream like a maniac. At this point they'd have zero regard for their own well being.