RotRL Wednesday Nights
Also known as the “whispering spirit”, (Probably from being caught sleeping all the time!) Malfeshnekor was a creature of great power trapped inside Thistletop.
Tsuto’s Journal made reference to it, and there was goblin artwork that depicted it as a 30-ft tall goblin.
The party was initially routed by the beast, but soon returned to smack him down handily.