I find Mind Sear to be very effective, especially whilst in Void Form. The insanity generation is great and even better before, if you take Void Ray too then Mind Sear does respectable damage. That in conjunction of ticking DoTs provides us with more than enough damage and Insanity. We get buffed and people still moan about how weak Mind Sear hits outside of VF, be thankful it actually hits harder now. Even before the buff to it, it is just a filler spell and you should have been casting it anyway as a filler on 3/4+ targets.