A life draining rift found in the Phlogiston, they are known as a Dark Region due to the ominous blackness of the clouds or Phlogiston found within the region. Living creatures who spend even a little time in a Dark Region will begin to lose their life essence (HP Loss).
The Weird is the most notable Dark Region in the known universe.
"The blackness is utter and complete, and seems to have no concrete shape of its own. Even in the short time you've been watching it, the cloud has shifted ever so slightly."
References
- Spelljammer reference: SJA4 Under The Dark Fist
- TSR reference: TSR 9325
- ISBN: 1-56076-131-8