DM/Inv. It is an indestructble powerhouse that just doesn't quit!
Regular self heal and -ToHit on everything from DM.
Softcapped typed defenses which can get to 59% without Barrier, for Incarnate content.
Capped S/L resists, and 30 to 50% for the rest, including Psi with the use of specific IOs.
Perma capped HP.
Taunt aura that gives you +ToHit.
Can IO out to get perma (or near) Haste and Soul Drain.
Endurance refill from DM.
DM/Inv is a classic combo. Softcapped defenses, high resists, capped HP, and DM to help with frequent heals and -ToHit.
For my build I have perma hasten, perma dull pain, and near enough perma soul drain. They really compliment each other well, and you can build quite the unstoppable powerhouse.