This event is a teleport cristal who only emits light when it is activated (in my exemple by switch 211, but it could be the 'event proximity' self-switch).
Page 1: parallele process who automatically set the kill switch (C in my case) to on
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Page 2: The deactivated state page. It doesn't emit any light since the 'kill switch' is on.
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Page 3: what you want to show when the cristal is activated. The kill switch will be off when you are there (see next page), so it will emits light.
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Page 4: when the cristal is activated, switch off the kill switch.
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Note that if for whatever reason you want to deactivate the cristal by setting switch 211 to off, you will go back to the deactivated state.