Best Primary for Force Fields

... Other than Robotics? :P

Well, the reason robotics/ stacks well is the exponential nature of layered defensive buff mitigation. As such, Thugs/ is an easy one. That said, Demons may work well...layering your defense with their resists seems a good thing. Oh, yeah..the big demon is defensive based, so there's some good defense stacking for you. Necro/ may work well once you have self heals...they get hit less, but can heal when they do. You'll just have to be careful with the knockback parts of /ff, as necro/ is melee.

Well, the reason I said no Robotics is 'cause I had a Robotics / FF Mastermind, but the bots were too noisy for me. :P

Ninjas works quite well. I made a Ninja MM that has every minion above the softcap to all three positions with the 5% defense aura IO. Your tier 1 Genin will still die, but the tier 2 Jounin and the tier 3 Oni are beasts.

With maneuvers on the enforcers, thugs can be easily softcapped with the FF secondary. Necro/FF can be brought very close the softcap, with two +5% defense IOs and a slotted up maneuvers. All the -to hit will push necro minions effectively well over the softcap, which helps for mobs that have defense debuffs. Ninja can also be softcapped because of their inherent +defense totals.

Of all of the available choices, though, demons are to me the most intriguing pairing for FF, based on purely on thinking through their capabilities. A key reason is that all the -resistance that demons do, and the exotic damage types, means that demons will hit hard even with an almost purely defensive secondary. Also, the -recharge in the demon prince stacks very nicely with softcapped defenses, plus the relatively good inherent resistances of demons add another layer of mitigation. With the ember demon taking on healing duties, and the potential to put recharge intensive IOs into Hell on Earth, a well built demons / FF will be borderline broken for most in-game situations.

I lean towards Demon as well. FF has a lot of skippable powers meaning you can take Hell on Earth and personal attacks without sacrificing too much.

I have a DS\FF and layered RES + DEF is very nice (plus lt's that heal single and AOE wise). Also one of the selling points is the demon prince has +DEF already and soft capping him with FF is really easy. Consider a soft capped melee boss pet....it's actually a nice thought . Problem is my DS\FF has stalled out in the 30's because honestly I have a serious love\hate relation ship with having to buff my pets every 4 minutes...individually.

I've since built a DS\Traps and I'm much happier. Still able to soft cap the prince, but no need to shield everyone every 4 minutes. But if you don't mind shielding pets, I'd put in my vote for DS\FF.

It's primarily for solo with IOs, although I'd occasionally bring him to Rikti mothership raids.

I'm looking at Force Field, because, honestly, I just hate not having mez protection. :P

Just be prepared. No matter which primary you pick any mastermind with /ff secondary will be boring as all hell. Force fields take twice as long to cast as other shields and has no activeness past Force Bomb. I have a 50 bot/ff. He's unkillable but I literally fall asleep while playing him

Eh. I've always said, if it's boring/easy, it's an excuse to crank stuff up. My forcefielder was set to invincible after level 22...when the new settings hit, she never dips below x6. in fact, I have to notch up the x8 to at least +1 or +2. But on the plus side, It's one of those that could defeat archvillains without losing a single minion.