“ A small, primitive village has yet to discover fire, which is a good thing because there are highly flammable (but not otherwise dangerous) gasses in the air. The heroes, blissful in their ignorance, don't know that and think it a wonderful idea to show the locals open flame.”
“ A magician develops a new way to make scrolls and can sell more powerful spells for cheap. Problem is, whether the magician is aware of it or not, the spell's power comes from spirits trapped by the magic that makes the scroll. Once used to power the scroll, the spirit is driven mad by the forces that have ripped through it's being, and often develops a homicidal thirst to destroy the one who tormented it. The spell the spirit was used for may have left some residual power in the spirit to give it more abilities than it ever used to have.
Buyer beware!”
“ It is dreadfully rude to carry a fishknife whilst talking to a Merman or Mermaid, as they think of them as we would think of thumbscrews or other torture devices.”