Training Iron Skin

Assuming stealth is 10, remove all armor. Barring that, try to get AC to around 10. Try to get items that regenerate health. Let monsters hit the guys you want to train, again and again... I only reached about 60 because I only wanted to prove the technique worked and wanted to save the training time to gain BOTH iron skin and reflexion. - WithoutRemorse

The best place to train Iron Skin is in the monastary in the jail cell with the 3 roaches. Just don't kill them in the beginning of the game. Come back when your around level 10 or so and take off all your armor ( hopefully you don't have stealth, but if you do, they don't have anywhere to run ). Even if you turn up the difficulty to expert they only hit for around 5 damage each.

There are several items that will make it much easier:

Ring of Regeneration ( best place to get is from Davy Jones Locker )
Infinity Helm ( Ferro )
Robes of Rejuvenation ( Ferro )
Amulet of Healing ( Crock )
Excalibur or any weapon that has health regeneration. ( Davy Jones Locker or Rapax Queen Chest )

There are also several items you can equip that will offset armor bonuses from your regeneration items. Most are imported from Wizardry 7:

Cap of Wiles -4
Magnetic Boots -5
Silken Gloves -1
Oliveskin Leggings -2
Shield of Soaring -3
Deathmail -8 / Oliveskin Doublet -2

Some of these may or may not be wearable by your character. Basically the idea is to get your AC down to a level where the monsters can hit you, but you can regenerate the damage each round. If you have your AC as low as it can go, but the monsters are still missing all the time, try turning the difficulty to expert.

Try to balance how much the monsters hit you, with your regeneration. If they hit you for 6 damage a round, you need items totalling +6 regeneration. If you don't have it, then you need to make them hit you less ( more AC or turn down the difficulty ).

The whole idea is to get it so you can leave the game running overnight, since iron skin takes a LONG time to train. - TinyMage