[Polkageist]

Oh yeah, then the DF Companion 2 that was linked is the best resource. The details that it'll have filled in about the villain's backstory will likely clue you in to how they'll set up their defenses.

Part of it though I think is reading the party composition and setting up the challenges to, well, challenge them. So that party of thieves will look to use stealth to bypass detection, so the dungeon is set up to provide interesting things to dodge, duck, and bamboozle.

If you're working with premade bosses, and you really want to use say BigOrc the Slayer as an opponent and you have a party of squishy thieves you may have to work a bit harder to make the boss' lair something the thieves can and want to tackle.

I'd have a boss like BigOrc set up his detection and security around having lots of boys standing around as sentries, and generally be in the middle of a giant ork-party all the time. Really that's the place any proper orc wants to be so hardly a bother for BigOrc. Orcs are always looking for a fight so there'll be lots of scouts, sentries, etc. wandering around the area and in the camp in case someone's nearby (they can fight) or trying to sneak into the camp (so they can fight 'em). If a party of heroes are spotted, then the boss response is simple, go fight 'em! With lots of friends, all the other orcs want a fight too! BigOrc is pretty simple, but very hard in a fight so he'll play to his advantage and try to engage as fast and as hard as possible since that's his strength. Subtle traps and ambushes just waste time to BigOrc.

EvilWiz is much sneakier. Magical detection traps will be scattered around everywhere, and he may have enlisted the services of a spirit or three to act as sentries patrolling around. They're invisible wisps so it's unlikely that they'll be detected and once they spot something they'll rush away to report to EvilWiz. Silent alarms abound since EvilWiz likes traps and doesn't want any interlopers to know they're doomed until its too late. If the heroes are spotted on the way in EvilWiz might start taking action, but could very easily delegate it to a subordinate as he is a very busy evil wizard. The lair will probably already be prepped to repel or entrap invaders, so some kind of misleading pathway may appear to lead the heroes into a trap or ambush led by the lieutenant. EvilWiz himself may direct the response, but he'll do so at arms length since the last thing he wants is a direct confrontation. He's knowledgeable, so will gladly use divination to get info on the party before taking action and rely on the lair's confusing layout and preset traps to buy him time. Probably very slippery and the heroes may need to destroy a couple of lairs in order to exhaust EvilWiz's resolve and resources as EvilWiz would rather run away and fight (or seek REVENGE) another day.