Forneus

The demon lord who lives within the Black Pool in Ravenwood, encountered in Ignoble Assets#Demon Hunting.

One of his physical forms, from GM notes:

FORNEUS, The DEMON within THE TAR is listening. 
12' tall Humanoid, horns, naked, raging mushroom erection,  
No eyes or mouth, only oversized fanged frog mouth. 
covered in dripping, stinking black goo.
* scorpion tail (2d6 burning poison damage, plus HT-3 or suffer Horrible pain for an hour), 
* long reach of 3, tentacles for arms. Its touch drains d6+2 fatigue.  
* Or it can grapple (ST 18). 
* Bite is d6 impaling, plus HT-1 or contract DISEASE.... 
  reduces max fatigue by 3 a day to 0, then HP until healed or dead.