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- A magical sensor, which detects magic weapons, activates a spring-loaded mechanism in order to put a new barrier in the way of the character.
- A visual sensor in/on the floor activates a clockwork mechanism in order to put a new barrier in the way of the character.
- A natural and permanent danger here activates a arbitrary mechanism in order to put a new barrier in the way of the character.
- A rigged container/door/opening at the entrance activates a arbitrary mechanism in order to put a character in jeopardy.
- A natural and permanent danger here activates a hydraulic mechanism in order to put a new barrier in the way of the character.