A short excerpt from the book, "Unpopular Tourist Destinations: a visitor's guide to the lesser-known demi planes".
The Demi Plane of Phlegm
Planes don't come much nastier than the demi plane of phlegm. It bears some resemblance to the elemental plane of water, being a seemingly endless sea of fluid lit by a diffuse glow. However, the similarities end here.
- Physical Traits
Gravity: Subjective Directional Gravity
Time: Normal Time
Shape and Size: Self-Contained Shape
Morphic Traits: Alterable Morphic - Water-Dominant
- Mildy Neutral-Aligned
- Normal Magic
Most of the plane consists of a thin white sticky fluid. It's possible to swim through it, but water breathing does not enable creatures to breathe in it. Anyone arriving in the plane outside its few air pockets is susceptible to drowning. Once a day, a DC 20 fortitude save is required to avoid becoming sickened and nauseated for one day from the sheer disgustingness of the place.
In some areas, the phlegm is thicker, and other colours, including yellow, green, brown and streaked red with blood. Movement speed is halved in these areas, and the fortitude save to avoid being sickened and nauseated is raised to DC 25.
The only known inhabitants of the plane of phlegm are oozes, which are immune from its sickening effects. They feed on the remains of visitors who have drowned in the phlegm.
The plane is believed to be a self-contained shape; certainly nobody has yet discovered an edge to it. However, very little exploration has been done within the plane due to the hostile environment, unfriendly native wildlife, and the fact that a gelatinous cube squelching its way through a patch of thick brown phlegm is one of the most revolting sights the planes have to offer. Now and then there is talk of building a sealed vessel in which to make a more thorough exploration of the place, but so far even the most hardened of planeswalkers refuse to volunteer for such a mission.