But I don't have a build for it. As Venom says, it's just use what you find. My necro used an Ancient Plate with 24% FHR and two perfect skulls for the entirety of Nightmare. I found Duriel's Shell, which is an exceptional armour. Made it unique using the cube and it is DIVINE: high resistances, high defence and cannot be frozen.
Also, basically all my gear is +res. Bone armor apparently only absorbs physical damage, so gloams are still freaking deadly.
I find decripify to be incredibly helpful. Together with Bone Wall/Prison it stops pretty much everything. Mud golem is a nice distraction and also slows stuff down. I've never actually used confuse and the like to great effect, so I can't talk about those curses.
Also Decripify/Amp Damage together with Corpse Explosion is really cool. Use the bone walls to keep the enemies together and you can get a cool chain reaction going.
Do note that when breaking immunities, lower resist effects only work at 1/5th of their actual capacity. There will still be creatures immune even if you use Lower Resist + Conviction (Hell Oblivion Knight has 180 Cold Resist, so it would take 81*5=405 lower cold resist to make cold actually hurt him.
Still, giving a creature with 50 resist -10 instead really helps killing stuff.