At the end of the hall is a wooden door with a metal frame.
Type: mechanical; Perception DC 22; Disable Device 22
Trigger touch; Reset None
When the door is opened, the metal frame snaps down on the character like a mousetrap. Mousetrap(DC 19 Reflex Save or take 2d6 damage and become pinned. CMB vs. 22 CMD to Escape)
Even though this might not kill anyone, the visual imagery of this trap going off is worth its weight in gold. If you really want to make this one memorable, have this be located at an entrance to a giant’s lair with an oversized cat. Perhaps that cat can even enter the room through a large pet door. If your PC is soloing it, have some dire rats appear as soon as he is caught.
A door is probably the most iconic dungeon element there is. Doors get stuck, the locks are trapped with needles, they are protected by runes – players can expect almost anything from a door. So, if you want to make an impression, make it different and make it flashy. For example, you could add a puzzle element to the following trap, one that requires them to “unlock” the two door rings as the only way to open the door.
Large, wooden double doors lead to the next room. Each door has a solid iron ring pull.
Type: mechanical; Perception DC 27; Disable Device 24
Trigger location; Reset None
When the rings are pulled together (the door will not open otherwise) they become shackled and constrict around the character’s wrists. The doors then open up wide, stretching out the character. (6d6 damage plus 1d6 bleed damage per round until magical healing is applied, DC 24 Reflex Save negates, DC 24 Strength or Escape Artist check required to escape)
This would be a pretty good way to start a boss fight, would it not?