Transcription:
probablybadrpgideas:
Give your players a "disintegration gun".
What it actually does is shoot people into the future. In the final session all the people they shot with it blink into existence around them at once.
celticpyro:
OP please change your url
If I was to do this, whoever gives them the "disintegration gun" would give the players a cryptic warning. Something like
Maybe a bar that fills up. Release happening once capacity is reached