# Black Dragon ## Regional effects _Source: Monster Manual (2024)_ The region containing an adult or ancient black dragon's lair is warped by its presence, creating the following effects: - **Acrid Haze.** Odorous and stifling fog covers the area within 1 mile of the lair, rendering that area [Lightly Obscured](3-Mechanics/CLI/rules/variant-rules/lightly-obscured-xphb.md). Travel for creatures other than the dragon and its allies takes twice the usual time in that area. - **Foul Water.** Water sources within 1 mile of the lair are supernaturally fouled. A creature that drinks such water must succeed on a DC 15 Constitution saving throw or have the [Poisoned](3-Mechanics/CLI/rules/conditions.md#Poisoned) condition for 1 hour. If the dragon dies or moves its lair elsewhere, these effects end immediately.