Mind/Emp is a very good combo. It shines somewhat more on teams than individually.
For APPs, take a look at Primal. Both Mind and Empathy benefit a lot from Power Boost, and the knockdown in Energy Torrent is extremely helpful because Fear'ed enemies (who can normally retaliate when you hit them) miss their chance to act if you knock them down with the attack.
Basic advice on Mind Control is to take as many powers as possible. The skippable one is Telekinesis but even it has its uses. Some people skip the AoE Sleep. IMO this is a huge mistake with this set.
In Empathy, the most skippable power is probably Absorb Pain. You probably want everything else.
In terms whether to IO, both Mind and Empathy benefit tremendously from +Recharge. Since you're a team heavy character anyway, my advice on IOing is to basically ignore Defense and go no-holds-barred after every scrap of Recharge you can get. The difference once you've worked down your recharge is rather stunning. Mass Confusion and Total Dom on 60 second recharge means one or the other is up every fight. It's great stuff.
You should plan to take Super Speed or Stealth, and slot it with a Stealth IO. The difference with and without some kind of stealth is night and day for me with Mind Control.
Why is stealth vital to a mind/emp?
Mind has three very useful aggro-free powers in Mass Confusion, Mass Hypnosis, and Confuse. Having a bit of stealth allows you to move ahead into an enemy's normal perception area and use these powers to hit the greater part of a spawn. Without some stealth you may be a bit more cautious and miss a few of the enemies that stray towards the back of the group.
Also, if you're considering this combo then I strongly suggest considering Power Boost. It's very useful for increasing the duration of your controls and increasing the the strength of your heals. Where it really shines is when used with Fortitude. A well-slotted Fort can provide 18% defense, but a well slotted Power Boosted Fort will break just over 31%. That's as good as Forcefield's ally bubbles and it covers psi defense as well.
If you want a "healer that attacks", roll a defender. THIS is a "Controller that buffs". You have a LOT of AoE mezzing potential: AoE sleep, AoE hold, AoE confuse, and cone Fear. TK also holds 5 guys (though often pushes 3 or 4 of them away). And your Single-target Sleep can one-shot mez most AVs. If played right, between your Mezzes, Fortitude, and Regen aura, you really won't be healing your allies all that often in late levels.
Where a Mind/Emp really shines in Hamidon raids. Not only are your buffing abilities in high demand, BUT, Mind Control is the ONLY set in the ENTIRE game capable of effectively hurting ALL THREE types of mitos. You obviously have holds for greens, but since your first three attacks don't have a "type" denoting melee/range/aoe, you can hurt yellows and blues, which have high defense against ranged/melee attacks, respectively. As a bonus, they don't seem too resistant to psi attacks, either.
You'll be a support powerhouse. Soloing will be slow and... well, slow. So, team a lot =)
-STEELE =)
Allied to all sides so that no matter what, I'll come out on top!
Oh, and Crimson demands you play this arc-> Twisted Knives (MA Arc #397769)
Although I'm not going to be working on this toon for a bit I just wanted some input before I started working on him, as mentioned in the title he is going to be a Mind Control/Empathy Controller. I've never really actually gotten to work with Mind Control a whole lot so I definitely need input on that, if anyone does have a Mind/Emp troller I would not mind some shared experienced, how does it play, is it more than a healer with some attacks for when the team is not dying?