Black Sand

A dangerous and mysterious substance that is scattered throughout the sand and is attracted to magic. Those that have seen it claim to witness the sands form into an amorphous mass before consuming sources of magic that surround it - objects and creatures alike. Various different peoples/cultures have developed ways to deal with both the sand itself and haves ways to protect themselves from these seemingly sentient amalgamations. However no one knows how it forms or if it has a goal. The debate further extends as people question whether it is one creature, a collective, or simply a construct with no life to it at all.
For this reason, cities in the areas the sand has been spotted essentially never “go dark” and have constant street lights and lamps in homes, etc. to be able to be on guard at all times.
Black sand is also thought to be a magical amplifier so mages want to study it, but its chaotic and dangerous nature make this seen as the quest of fools.