“ MoonInk: This alchemical product has 101 uses. The Ink/Paint dries to be totally clear and almost unnoticable. Under moonlight, it comes forth as a silver ink. It was originally used by the Elventi to enhance certain pieces of art. It is used by espionage types to produce secret messages, nobles for hiddle plots, and diabolical cultists to write their spell books (usually in books of holy texts, to throw off people reading it).”
“ Mining in a certain area turns all exposed skin (maybe just parts that are actively disturbing the chemicals that cause the reaction) of the those doing the mining to a dark blue color. Will wear off taking as many years/days spent in the mine.”
“ The player characters, experienced and somewhat well known, hear rumors and travelers' tales about a distant area being overrun by dragons (or other terrifying monstrosities). The locals have sent them a message, begging for heroic aid.
When they investigate, they discover that nothing of the sort is going on. It turns out that a group of thieves wanted them out of the way so that they could rob them (or someone who would normally receive their protection).”