Dungeons: Every Adventurer's Nightmare.

Just a short posting to mention one of a DM's best assets in terms of environment - the dungeon. Many a fledgling adventurer will recall his or her delve into the murky, cobweb-strewn coldness of their very first dungeon - and if you really pay attention, you'll even see that far away look in their eyes as they re-tell it.  No matter the outcome: good, bad or disastrous, they will remember it