Ancients

The oldest and most powerful of all monsters. Nineteen of them rose during The Rending. They reside in the sixth strata of the Dungeon. "'Their power was overwhelming. None could stand before them, when they moved, cities fell, nations crumbled and people died. Like immutable law they were heedless of the plight of mortal, more akin to the forced of nature than creatures.' Excerpt from 'The Gods of Rending' in the imperial library of Shuth, Author unknown"

Ancients' names

 * Yarrum the Eternal Worm
 * Theorazzn of the Decaying World
 * Syssernix the Dark Spear
 * Morribolg of the Fetid Earth
 * Carriflare the Hell Flame
 * Rigorite the Mountain Breaker
 * Tarriglyx the Hunger
 * Arconidem the Demon God
 * Zothoth who Feast on Sanity
 * Torra the Dread Dog
 * Gon the Sightless Freak
 * Yolesh the Ever Dying
 * Lerrewyn the Grasping Tree
 * Horgran the Butcher
 * Perrianon of Blood
 * Kygar the Storm Bringer
 * Ruminominex Shaper of Earth
 * Braxxin who Froze the Sky
 * Odren the Father of Monsters

Known Feats
Yarrum the Eternal Worm dug a tunnel 300 meters wide beneath the capital of the Empire of Stone. So it's possible to assume that Yarrum itself is around 300 meters thick. He battled the Golgari for several years, consuming all in his path until the receding mana levels forced him to go back to the Dungeon. There are records of Yarrum talking with at least 2 shapers: Igniun Faranon and Irrin Stelix. The former was the greatest shaper of the ancient Stone Empire and after the communication with the ancient, she decided to retreat from the public while keeping the contents of the conversation secret. The latter after communicating with Yarrum created the secret organisation that is known as the Cult of the Worm.

Kygar the Storm Bringer after reaching the surface caused lightning to fall for a month, burning all to ash.

Arconidem the Demon God was another ancient that communicated with sapients, in this case, a powerful Kaarmodo wizard. He's the author of Red Truth (the sacred texts passed down in the Conclave of the Red Truth) and rules over the demon society on the 3rd strata from far below.

Morribolg of the Fetid Earth turned the ground to mud over a vast area, sinking the entire city of Yallowyn beneath the ground in less than a minute.