Ordrak is the final boss of Torchlight and stands head and shoulders above anything seen up until him. The fight can take new players by surprise by being an order of magnitude tougher than anything experienced so far. Playing as a very hard / hardcore character I rather not get all the way to the end boss and then dying as that would be rather depressing. How should I prepare for the fight to have the chances overwhelmingly in my favour?
While I have not played through on the hardest difficulty, on the other difficulty modes I have played, the monsters in the main quest levels do not scale with player level (this should be easy to check by popping in to level 1 of the mines well after you have left them.) At one point I was going through earlier levels to get magic items for ember and was surprised by how quickly I was still gaining experience against low level monsters. If you are willing to grind, you can reach very high levels, but be careful, outside the main quest levels monsters will scale to be just a level behind you, and monster power scales faster than your own with level, so don't go into phase portals, map scrolls or that "hatch" guy's missions when you are well above level.
Also, like most bosses in the game, Ordrak is most dangerous at close range. Not that he is not dangerous at a distance, just less so. This tendency has always made the Vanquisher the easiest class in my experience, even if she is somewhat fragile. I was recently surprised by the effectiveness of her Flechette Trap. It fires fast enough that the reaction animations of the enemies can slow them down, and of course her explosive shot is very good. I am less familiar with other classes' abilities.
I hope that information is in the sort of vein that you were looking for.