Dead Man's Chest (3.5e Equipment)
From D&D Wiki
Dead Man's Chest: The PC's enter a room with many bloodied swords on the walls. The blood on these swords looks fresh (an illusion as part of the trap). There is a coffin in the middle of the room that looks totally new and polished. If the players open the coffin, the swords on the walls detatch themselves and fly around the room, slicing at the players. The swords are only illusions, but there are very real, invisible darts coming out of the walls. If someone gets in the coffin and closes it, all of the illusionary swords impale the person. Then a horrible, blood-curdling scream issues from the coffin. In reality, the PC inside was transported to a different room and a Magic Mouth made the scream. The sword fly back to the walls, and the trap begins again if the players once again open the coffin to check on their "dead" buddy.