Ghostly flaming apparition of a blade, slayer of spectres and all that is ethereal, wielded by its durable hilt inlaid in gold, silver, ivory and white pearls. It can turn the tide when fighting the intangible.
Deeping Steppes as named by Dargain the Gnomish adventurer who happened upon this place when attempting to find lost friends in a nearby series of caves and was swept in by the unexpected surge of an underground river, perhaps due to shifting of plates or erosion of a natural barrier. The cavern was sealed and unknown until being discovered by Dargain.
This is a region of the underdark where a series of very large plateaus occupy a huge underground cavern. The cavern is situated near a very common and sometimes treacherous underdark route know as The Underway (in my version of the world) which reaches from the Dales to Silverymoon regions in the Forgotten Realms.
In one region of a forest, all of the trees are identical, down to the leaves and the twigs. If the PCs carve something into one of the trees, it could mystically propigate until it covered all of the trees, or could vanish since it was not carved into the one true tree.