Robots, power pools, and things staying put

I have two robots characters at the moments, one robots/force field and one robots/traps. I'm pondering the last few powers for each.

Mu Mastery's Electrifying Fences is more appealing the tougher my assault bots get. Two questions.

#1. How does it compare to Soul Mastery's Soul Tentacles for the specific purpose of keeping targets stationary so that they can burn more? (And, more generally, how do the two patron pools compare for robots purposes?)

#2. I'm not, at the moment, seeing anything in the hero-side epic pools that offers anything like the same AOE immobilizing utility. Did I just miss it, or is this a real gap that is likely to justify my taking characters villain-side long enough to get their patronage?

I run a Bots/Pain soo my needs are a bit different but i am in the process of becoming a villain to get either mace or mu mastery i figure i will choose which i want more Res or Def by the time i become a villain..

I am still pretty new so i can not answer your questions as well as i would like but from what i've seen and read the best Epic on blue side for MMs is cold mastery.. which although lacks AOE holds does have some pretty amazing powers..( haorfrost/hibernate) for me it was more about theme ( why would a robotics engineer have cold powers..) and the fact that the cold armor messes up your looks. I didn't want to be all icy and blockie.

I can tell you this, what i do know is that Fences is popular because of its -kb so it is used by a lot of Bot MMs to keep the mobs in the burn patch. Though from what i've read is has a small area of effect. For me i think i am leaning towards mace.. as i too want the AOE holds and need the protection since Pain lacks Def powers i figure i will pick it up in scorpion armor. Since both of yours have force fields you may want to go to Mu for the resists..

Hopefully someone with more experience comes along with more help and/or to correct me

While I don't have any experience myself with fences, I have been told it is better for holds then tentacles due to it's Targeted AOE nature rather then a cone. I have had experience with Web envelope and soul tentacles both and to be honest, as someone who normally loves /Dark tentacles, I couldn't stand them. I much preferred the Web envelope. That being said, I have heard it is very comparable to Fences and, like you, going with Mu Mastery on both my MMs.

As far as Hero epics, everything I have seen shows ST Holds at the most.. and pretty much any AOE is pitiful, outside fireblast.

Thanks very much, folks! It sounds like I'm not missing anything obvious, and that's reassuring.