Twilight Mushrooms

Twilight mushrooms are purplish-black mushrooms about 4 to 6 inches in height, growing in patches of 5–10 mushrooms and are only found in damp, dark underground areas. When these extremely sensitive mushrooms react to vibrations by releasing a cloud of noxious, choking spores. When a creature moves to within 10 feet of the mushrooms for the first time or starts its turn there, it must make a DC 12 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much damage on a successful one.

Sunlight renders twilight mushrooms dormant, and any amount of cold damage instantly destroys one patch of twilight mushrooms.