Crypt of the Crystal Pools

Deep underground is a special cavern. It is known to those few who are privy to the knowledge as the Cavern of the Crystal Pools. The name is derived from the six, ten-to-twenty-foot pools in it, and flawless natural crystals growing from the ceiling thirty feet overhead. When light present in the area, its otherworldly beauty becomes apparent. Rainbow patterns scatter through the crystals and the sight is made all the more stunning because the vast canopy is reflected in the mirror-like surfaces of the pools, which appear as if they were filled with crystals themselves.

Those serving the gods of nature discovered the cavern long ago and it became a meeting place, and one of quiet meditation. After a while, they decided to build a crypt here, and dug it into one of the cavern walls. Once complete, deceased devotees were interred here to slowly decompose and give their lives’ nourishment back to the ground they came from. The crypt was a serene place of peace, remembrance, and respect. Unfortunately, it wasn’t to last. Its seclusion kept it secure, and that security was taken for granted.

A giant rat was searching for food when it found the entrance to the underground. It followed the passage until it reached the cavern. In its quest to eat, it found the crypt, snuck inside, and fed on the interred. This caused the rat to develop a malady (though whether magical or natural, none are sure yet). As it consumed the dead, it grew and grew until it could not fit in the crypts anymore, instead having to settle for lairing in the cavern at the crypt’s entrance.

The beast is colossal. It stands 25 feet tall on all four feet, its body wracked with fetid disease. Its fur seems perpetually matted and moist, thanks to a mixture of the humidity and the putrid fluids constantly issuing from its sores and wounds.

During the day, the rat rests in its nest; a heap of old and new bones that are marrow-drained and scraped clean. After consuming most of the crypt’s corpses, the rat began venturing back to the surface in the evening to hunt. Luckily for the rat, the passage and entrance were large enough to accommodate its size.

Since moving in, the rat has acquired a gluttonous appetite for the dead. It prioritizes eating corpses over anything else. It can sense dead bodies nearby, and can smell one (even buried) within 100 feet of it. Upon it has found a body, it will retrieve it, consume it entirely, and return to home to promptly regurgitate the bones onto the nest. The rat also prefers to eat in peace. Any living creatures in the area where the rat has uneaten food is considered a threat, which it will attack relentlessly until no more threats remain, only food.

Suggestions:
 * Druids or rangers need help clearing out the rat.
 * Rat occupies a 20-foot-by-20-foot square. Alter stats to reflect a creature that large and powerful.
 * Give the rat a poison cloud ability that lingers in a haze around it.
 * The rat may only target those who don’t flee or are carrying/near a dead body