“ In some virtual forums going AFK is the equivalent of passing out drunk on the couch at a fraternity party. Everyone from hackers to everyday participants will take shots at you, and you can expect your avatar to look very different when you get back. Hopefully you will notice quickly.”
“ A powerful wizard that the PCs encounter is completely silent. He does not speak and cannot be heard as he moves. Even his spells are silent, but his magic is just as potent.
He has a tendency to summon invisible chairs, place foes in invisible boxes of force, and other 'mime tricks'.”
“ A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.”