Since the guy who started the topic is apparently not here, I will take a courage to answer these questions (since I just have completed 100th wave in Survival mode and got bored).
> any cheats? =D No known cheats. There is a glitch though - after the survival mode game reset you end up with your party, fully gathered and equipped, and with 100.000 gold pieces again, and restocked store - means you can endlessly improve your party, collecting the best matching pieces of equipment from the store. (No I didn't use the glitch to beat the survival mode).
Original Monsters' Den features only one campaign: The Den of Corruption (with 10 levels of dungeon). Monsters' Den: Book of Dread features an additional campaign "The Den of Terror", which can be finished on dungeon level 9. Book of Dread also features a totally new "Survival mode", in which you fight endless waves of monsters (that increase in power every 20th wave)as long as you can survive.
steevo15: Is there a max amount of levels? or is it infinite?
You can go as deep into every dungeon as you want. There were reports (apparently fake) that the game ends on level 250 - you are welcomed to check it out yourself
You probably mean The Corruptor, final boss of first campaign - Den of Corruption:
He is pretty nasty - because in addition to his powerful attacks he also summons evil copies of your party members to fight on his side.
The ways to beat them differ - from simple 'hacking' the copies, trying to use 'banish' conjurer spell to destroy clones, or even undressing your characters - so your characters will not be so powerful (and so their copies as well) (there is a video on youtube featuring this strategy [url=http://www.youtube.com/watch?v=AncSvvXcnOM])
It depends on the character class you want to give the item to There are several items of 'legendary' quality. The most guaranteed way to get them are fights with campaign bosses and legendary monsters. Legendary items are quite powerful - for example Demonhide cloak from Corruptor gives you +5 to each stat and +4% chance to kill target as well as 56 armor.
I'm currently writing a guide and walkthrough for Monster's Den: Book of Dread and once I finish I will put it somewhere here as well, but meanwhile you are welcomed to check it from time to time for when I will finish with items section and put some screenshots there as well