Woah, I think I need to nerf Hymn Incantor!
I'm not sure Eclipse would be worth bothering with when you are focussed on darkness only.
And if you are going to unlock Umbra and Twilight you should get a bit more out of them.
Terminator is a bit iffy (I'll get it sorted one day), but Umbral Gate and Pitch Black are reasonable defensive talents. I need to buff the category a little so its worth the unlock cost.
For Twilight, I always get Mind Blast. Mass Confusion and Brainlock is excellent.
I got it for the penetration and the reset.
I just haven't invested much into it, i guess.
I've been meaning to invest in mind blast, I guess i just never found the time to.
A little bit of a starters guide written by yours truly here