Klacktel

Creature 20
rareMindlessSwarmUndeadUnholyVoid
Perception +34; Darkvision, Lifesense
Skills Athletics +37, Stealth +36
CHA +5
CON +10
DEX +6
INT -5
STR +7
WIS +4

AC 46; Fort +39, Ref +30, Will +32
HP 360 void healing
Resistances Bludgeoning 10, Piercing 20, Slashing 20
Weaknesses Area Damage 20, Splash Damage 20, Holy 20
Speed 50 feet, Climb 30 feet, Swim 20 feet

In places where the dead are discarded in such great volumes that the remains begin to feel more like terrain than bodies, in realms where void energy flows strong and seeks any fragment of once-life to infuse, in areas so suffused with negative emotions and agony like the Amaranthine Oubliette, it comes as no surprise that the cast-off remnants of prisoners over the eons have become monsters.

Over the eons, past wardens of the Oubliette have allowed some of these deadly swarms to escape into other planes for their own inscrutable reasons. Once stranded elsewhere in the Great Beyond, the pain of being cut off from the Void drives the klacktel into a relentless rampage that stops only when it is destroyed.

Cursed Treasure

As a klacktel rolls over anything that comes within its path, rubble and discarded items inevitably become swept up into its mass, adding to the tangle of bones. When a klacktel is slain, the bones quickly rot away into foul-smelling tar, but those items still remaining in its mass that haven't been ground to powder clatter to the ground. Magical items that have lingered overlong within a klacktel can become corrupted and cursed.