“ A new substance is found in an out of the way area and kept very quiet. It is found to make a perfect counterfeit diamond. Only the most expert of expert appraisers would even have a hope of noticing that it is fake. Only one problem: if it gets wet it starts to slime and if it is saturated, it turns into a glob of gel.”
“ 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.”