Tips for beating diablo in hell

[neversun]

You need Golem as high as possible (I've got Haridan's full Set with +to Golem Spell) and 3 basic spells for Sorc: Chain Lighting (CL), Meteor, and Bone Spirit (BS). Cast Golem, put one of these spells to the Left mouse button, "Teleport" to the Right one, go slowly, if you see a group of monsters - teleport away from them and make a few steps back, so a Golem will be between you and monsters and they will engage him, not you. Then spam Meteors, Chain Lighting, whatsoever. Very easy. Repeat with another group.
Bosses.
1. Gam'ar will fall very easy from Chain Lightning or Meteor, or Blizzard. (He and his Minions will be busy with a Golem, so just recast him as necessary).
2. Bloodlord might cause some problem if he kills Golem very fast, before Golem spell cooldown renewed. You always want a Golem to be alive with him. To prevent fast killing, do not allow him to hit Golem non-stop: allow him only several hits and then just teleport not far and again make a step back (same as you did before). He will lose a second-two to get engaged with a Golem, so you will get those seconds for it's spell cooldown gone to recast a new Golem again.
First use BS, then finish him with CL.
3. Benedict is the easiest one: just spam CL and he will not be able to do anything.
4. Diablo is the hardest one. Again cast Golem, turn on Elemental Drain and Temporal Slowdown. You need a staff with minimum -15% Target Resist Magic. I you do everything right, before Temporal Slowdown ends you will remove 70-80% of his life. Recast Golem, repeat with Bone Spirit, and then finish him with Meteor.
If, by chance you get under Diablo's Fire spread or Red Lighting just drink rejunerations like crazy.

[neversun]

With Rogue I had already Heartseeker in Hell difficulty, so everything was very easy except Diablo himself. I didn't expect this, and was really surprised. He just was smashing my Rogue down again-and-again, I managed to took maximum half of his life.
"Battle Master's Coat" with its +% Damage vs. Demon doubled my DPS and Diablo felt down in Hell.

[hldemi]

Done hell yesterday with rogue. I cheesed most bosses. Gam'ar and benedict are easy.

Bloodlord is hardest. He would kill me in a 3 hits and one charge. Dmg I did to him was so low that I would have to shot at him for a 4 minutes continuously to kill him. But I figured out that there is a very small gap in a distance where you can hit him with guided arrow and He will not aggro. Play on big resolution like 1960x1080 so that you can see him on the edge of screen while He is still to far away to aggro. Position yourself so that there is a wall between and calibrate your guided arrow over the edge but you have to do this very carefully.
Basically the technique is this: start shooting guided arrows while you are too far away to hit him but arrow still track him and He does not aggro because of distance. Then move so little that you basically click 1mm beside your character closer to him and shot a new arrow. Do this until the hit is registered and if done right He will not aggro not teleport. This still took me 4 minutes to kill him so regularly it would take around 20 minutes for me of perfect gameplay with no mistakes. I swear this worked or me. I will try to do it again and record If I manage.