Traps: I once took a page from Sam Vimes. The assassin needed to get into a mansion. At night. There were guards posted at the gate of the outermost wall, and no trees nearby, and a few hidden alcoves with guards. However the alcove-guards had terrible Spot/Listen, to reflect that they were more interested in keeping out of the rain and having a smoke. The top foot of the wall was designed to crumble with ease, and had iron spikes inserted. At the back, there was a single tree to climb to hop over... but some bastard had cleverly sawn through all the branches so they couldn't support any weight.<br/><br/>Once in, there was a hedge. With beartraps and assassin vines. The garden looked like the easiest way to get close without making any noise, but someone had the mistaken idea that if you plant caltrops and acid flasks, they'll grow into golems or something. The front door to the mansion had a fake lock - connected to a device of Shocking Grasp. Essentially, it's a fucking mansion, there's always<em>somebody</em>in there, so you never need to lock/unlock. You knock, and if you belong you're let in.<br/><br/>However there are multiple floors, and some balconies. The shed seems easy to climb... but some bastard decided to saw through the beams and just put loose iron sheets over, so walking across causes one to fall. They then dug a pit in the shed, and filled it with swamp dragons (more or less a swarm of 1/2 Dragon (Red) pseudodragons). Still, you can jump up onto a balcony... which has nails sticking up on the surface as it connects to an old storage room. The door is locked, and unlocking it from the outside causes a scythe to swish at knee-height.<br/><br/>One could also try climbing the walls: looking up shows that there are small decorative things that would make ideal handholds. Looking down from a height shows that actually, someone embedded razor blades in the walls at upward diagonals, so someone below would see a handhold, leap up, and lose their fingers.<br/><br/>Finally, there is a stable, which has a trapdoor for an emergency entrance/exit underground. Oddly enough the whole floor is oiled, meaning people fall over a lot. There's also a lot of hay and flour. And opening the trapdoor causes a bell to ring inside the mansion, so one could drop a torch there and ignite the tunnel.<br/><br/>It was a piece of mastery, but I had made it for a character that was good at dealing with traps. So the player was careful and smart about things, and the character abilities took over the rest - he took some injuries, but made it in and succeeded on the assassination.<br/><br/>---<br/><br/>Monsters: nastiest thing I recall doing was putting two shambling mounds in a room, and each one had two shocker lizards nested inside it. Each round, the lizards sent out a wave of electricity, hurting everything that wasn't a shocker lizard or shambling mound, and adding more and more Con to the shambling mounds. Seriously, if those plants had a Con-based attack, they'd have murdered the party. As it was, it took a very long time, and injuries were received. I was congratulated for being an evil bitch.