Pools of Wittebak

Wittebak was once a peaceful city of three thousand or more rock gnomes, a safe haven for the small ones built into the mountain rock and heated by a series of geothermal pools. The Wittebak gnomes weathered great wars by not getting involved, investing in contraptions and laughter rather than wars and empires. They found joy in inventing complicated ways to simplify their daily lives. Yet, for all their efforts, trouble eventually came to them.
Around four hundred years ago, a displaced band of hill giants found and luxuriated in Wittebak's hot springs and made a new homestead on their banks. It is said that Wittebak was founded underneath the full light of Ruidus, for by pure misfortune, a flaw in the stonework of the gnomish city cracked under the force of the giants frolicking within the pools. Worse still, the cave-in did more than simply crush a few buildings beneath. The seismic force of thousands of tons of rock collapsed into the caverns, cracking open buried pockets of volcanic gass.
Over a thousand gnomes suffocated that night or were incinerated in isolated gas explosions. The survivors fled into the mountains, assailed by hungry giants as they ran. The gnomes have found unlikely refuge in Kraghammer, but Wittebak has been abandoned entirely, choked by caustic gas and locked in a terrible moment in time. The ten-times great-grandchildren of the giants who caused the gnomes to flee now call the hot springs their ancestral home, and they flourish within their unchallenged territory.
Beneath them, the ruins of Wittebak are stratified into three distinct tiers of death and despair.

Tinker's Tier

This level is relatively unharmed, and the full glory of Wittebak's tinkering shops can be seen here; some even include marvels of technology unseen for centuries. Creatures that need to breathe can survive the gases in the widest, uppermost level for a number of hours equal to their Constitution modifier, and take 1d6 poison damage each minute after that time. The hill giants who live within have adapted to the gas and do not fear it.

Homesteads

The air in the middle level is heavy with gas, and the quaint gnomish homes on this level are filled with the decomposed remains of those too slow to escape. The entire area is lightly obscured with clouds of gas, and tiny streams of hot water leak from the walls, tumbling into the level below. The gas here begins inflicting damage after only a single hour.

Engine Core

The bottommost tier is a mechanical marvel, a titanic wheel of rusted iron and shining steel with no known purpose. This level is completely flooded and filled with merrow, and is the lair of a sea hag named Mauvlettir. Adventurers aware of the demonic origin of the merrow will find their presence here deeply unsettling—what was the purpose of the secret lower level?

Type

Spring