The only powers I ever use are Blink and Dark Eyes. They're all I need. Rat Swarm is useless to me because I never need to fight groups of enemies at a time, same applies to Windstorm. Possession was never really useful to me. I had an easier time getting through levels without searching for the little drains you can crawl or swim through. I never really used Bend Time, either.
Blink, Dark Eyes, Agility. As soon as I've upgraded those three, I've got a stockpile of Runes I'll never use.