Ikouse was born in some dark, foul-smelling cave, where he lived his first two months of life along dozens of his siblings. Scraps of rotten flesh were regularly thrown to their midst, but as they grew older, they became more hungry, and the food given to them didn't increase... Almost eaten by his bigger brothers, a fate shared by several of his smaller siblings, but proved fast and sneaky enough to evade them, hiding in whatever holes he could find. Stealing leftover bones to scrap down the marrow of his slower brothers. Ikouse soon learned to aim thrown bones at eyes to keep his hungry family at bay. Then to sharpen broken bones so they hurted more. Ikouse discovered he enjoyed hurting others...
Then an hooded adult took him, along with his surviving smaller brothers that proved fast like him. Given clothes for the first time. Ikouse liked it. Something he had never seen before. Then the training. How to really stab living things. How to properly hide in holes. How to observe his surroundings. Ikouse soon graduated as a scout after ambushing his other siblings one by one until he was the only one left. Not that he had been ordered to, it simply meant more food and clothes and weapons for him.
Ikouse was grouped with other azanideos, and rose trough the tunnels where he always lived. It was then that he found out that there were other kinds of living beings in this world. Orcs, goblins, and the few humans, a rare race since they couldn't see in the dark, so clearly they had problems multiplying. They all tasted quite good, even if you sometimes had to peel away unchewable metal clothes to get the tasty meat below.
As his mind developed, Ikouse also learned that the surrounding tunnels were controled by those other races, and they were many, perhaps even more than the Azanídeos It was his job to scout the food sources. To know the tunnels and the best paths, so he could guide his bigger, stronger brothers to eat them. A job Ikouse gladly did, reporting back to a central cavern where their rat warlord shouted orders and ate those that disapointed him. Also how to use more sophisticated weapons, special acids and explosives to make a better job. And to keep his head low when meeting with the Exalted: the azanídeos whose glorious corruption had allowed them to become something more. With claws and wings and spikes and armored skins. Only the rat warlord dared to look them in the eye. Great envy.
A big surpise came one day however when he was ordered to not try to eat orcs of the Humber tribe. Keep an eye on them, but not stab them them when their backs were turned. At least for now. Something about a "collaboration". They would fight with them to crush the other races in the tunnels, including the other orcs, then they would have the Humber tribe for dessert. Such cunning!
And the surprises kept coming. A river. Such a big body of water. Not oily enough for Ikouse's tastes, too bland, but the rat warlord said that could be solved. Soon other azanídeos were ordered to start throwing leftover filths from their people into it. The Humber orcs also reported about a village of humans on the "surface", a cavern so tall you couldn't see the ceiling, and a magic ball of fire flew above half the time, and a floating silver ball the other. Ikouse was warned to never go to that place. That they couldn't let themselves be seen in the surface by anyone. Still, the rat warlord commented that it would be nice if they could reach that village with so much food and treasure walking around. If only there was a tunnel leading directly under it... The humber orcs said that yes, such a path existed, but there was a great obstacle. The crazy chain lady. Ikouse was smart enough to evade assignment to the missions to try to directly deal with her. Many of his siblings killed by her, then not eaten, but rather turned into dolls. Such a waste of food. The rat warlord decided that they could bring the village under their fold by polluting the river enough. But still keep sending weaker troops to keep the crazy chain lady occuppied.
But today, something else was on the cavern leading to the surface. Completely new beings! Perhaps it wasn't very wise to try to take them on his own, but if he could at least take one down to get a taste...
Tukuyomi now has a good knowledge of the general tunnel outline of the area for some miles around. Main points of interest for you underground would be:
-Rat warlord cavern, leader of the Azanídeos in the area. At least five "Exalted" Azanídeos with him at all times, serving as his personal bodyguards.
-Umber orc tribe cavern, that seem to have allied with the Azanídeos. Infamous for taming and using Humber Hulks as pets and warbeasts.
-River cavern where they're dumping tainted stuff.
Each would demand having to break trough at least one minor outpost, altough you have enough information to directly teleport instead if any of you has such an ability.
There's also a couple pockets of kobolds and goblins around, the rest of the underground denizens in the area seem to have been wiped out by the alliance between azanídeos and Umber orc tribe. Enough left to still have a chance to fight back, but cowardly hiding in smaller tunnels where the bigger races don't fit easily for now.