The Pools of Wittebak are located in the Cliffkeep Mountains of Tal'Dorei, north of Kraghammer and between 100 and 120 miles south of Terrah. In a forest ravine not far from the pools there is a single small home which was inhabited by Sprigg. By 836 PD the area is considered a hill giant settlement called Gundergrunch.
Pools
The pools are a series of large, mineral-rich geothermic puddles across the mountainside. The puddles once brought various minerals up to the surface from the deep waters beneath the mountain.
On the side of the mountain, not far from the pools, there are large mounds of mud and scrap wood that hill giants use as homes.
Engine Core
Beneath all the remains of the once advance gnomish settlement, there is a strange, giganting wheel of rusted iron and shining steel of unknown purpose. In or before 812 PD merrows were living in that tier of the ruins, as well as a sea hag called Mauvlettir. By 836 PD it was known that at least one aboleth had its lair there, living with its servants even lower.
Forest
The chemicals from the pools have made a lot of the ground immediately near them unable to grow any significant plant life, but the area is otherwise forested. There are breaks in the canopy that let the sun in, and many forest animals including squirrels and wolverine-like creatures.
In a heavily shaded part of forest there is a small house. This is the house of Sprigg the Obnoxious.
Sprigg's house
As of 812 PD, Sprigg had been living in the house for about 37 years and Demistrik the imp had lived there for 19 years. After Demistrik's master died in one of the traps while attempting to get in the house, Sprigg gave the imp permission to stay.
The house was two-stories high and built to gnomish scale. Outside it were eight large, rusted, iron bear traps, but in front of the door was a welcome mat. Sprigg kept the door locked with six or seven different locks but it was not trapped. The inside of the house was very cluttered, with two bookcases full of books, papers, and scrolls. On the furniture and chairs were more stacks of books, sacks, satchels, quills, and inkwells—some spilled and left to dry long ago. There were four windows and a staircase to the second level. There was also a trap in the middle of the room that triggered an illusion of a beholder. On the upper floor was a door leading to a balcony.
Screenshot of battle maps of Sprigg's house from " The Fear of Isolation " (1x105).
History
Centuries ago, before the Divergence, this subterranean gnomish city was founded, if rumors are to be trusted, under the light of Ruidus. By the end of the Calamity it was considered the most advanced city in the continent, inhabited by thousands of rock gnomes. Around the first half of the 5th century PD, displaced hill giants moved to the area, disturbing the pools. A combination of seismic activity, the force of the giant visitors and the volcanic gas and toxic fumes from the puddles, freed through the cracks, caused the death of most of the gnomes living there, and the destruction of their home as they knew it, with the survivors fleeing to Kraghammer, where they founded the Cracksackle Union. Although the hill giants' presence and the influence of the Moon of Ill Omen were blamed for the tragedy, the rock gnomes themselves were responsible too. In their hubris, they boasted to be superior to their stone giant neighbors in the mountains, whose reaction to being called "ignorant" was to use their magic to cause the earthquakes that contributed to wreck the city.
The air surrounding the Pools of Wittebak became toxic to breathe, damaging any creature in just 1 hour. By 812 PD the only ones who were completely unaffected were the hill giants who still lived there, for they had adapted to those poisonous fumes.
After Vox Machina came to the house looking for the key to Ioun's whereabouts, the party was surprised by an attack from the followers of Vecna. During this fight the house was thoroughly wrecked, and Demistrik fled. Sprigg went with Vox Machina to find Ioun.
At some point after 812 PD the local hill giants turned the area into a proper settlement for them, calling it "Gundergrunch". In 836 PD they were ruled by Prince Gondalorr, a tender-hearted giant who was actually in favor of repatriating the rock gnomes that had once inhabited those lands, much to the displeasure of his much crueler sister, Gondabrau, who would rather devour the smaller humanoids.