Aldersberg [90x70] In this fortress, brave warriors fought their last battle against a demonic creature

This is the first dungeon I've ever created.
If you want to have certain things changed or a specific size or file type then just comment or write to me!

Here is the backstory of this fortress transformed by wild magic:

The events that lead to the devastation of this place were triggered by a defeat on the battlefield. The Paladins were defeated 50 years ago by the army of my vampire BBEG. Only the enduring elite Paladins survived the long retreat. Their leader hoped to be able to hide in the almost impregnable underground part of his castle. Instead of a long siege, my BBEG sacrificed the prisoners of the battle and called a demon of growth. These demons spread so much life that ultimately everything surrounding them suffocates (its attacks trigger the growth of plants and fungi in the body of the victim). It is an agile creature with a plant body. Tendrils and huge thorns are his weapons.
The demon stormed the fortress alone. Soon an organized fight in the main hall turned into a flight and wild hunt in the corridors of the castle. The demon took its time. Soon the last part of the knights had holed up with strong magical support in the north-eastern part of the fortress. Had they known how weak the demon was from their attacks, they could have hunted it down it easily. But they were shaken by the slaughter that had happened before and they were so tired…
Meanwhile, the demon picked up some of the wounded. In the armory to the southwest, he forced a paladin to slit their throats. With there blood he called the eye. He placed it in the room above and it began to cry. The liquid can decompose stone very quickly at the will of the eye and very quickly dug in the direction of the entrenched knights. The liquid also filled the air with magic, which stimulated the growth of the mushrooms. All mushrooms are directly connected to the demon and all blood they ingest strengthens him. He chained the last prisoners into the chapel and put threads of the fungus into their bodies. As long as they had blood in them, they strengthened the demon every second.
Filled with this power, he set out to face the last paladins. He broke through their ranks but was quickly surrounded. He inflicted countless wounds on them, but the brave warriors stood firm. They almost defeated him when the wall broke open and the flow of liquid from the eye spilled into the room. The liquid immediately seeped into all of the combatants' wounds and sprouted mushrooms. That was an incredible power boost for the demon, which triggered a huge magical detonation. The cave in the north-east was created. All were dead.
All? No two warriors had survived. The leader of the army was unharmed in battle (skill or cowardice?). He survived the explosion and fled through the hole where the liquid drains and finally emerges on the mountainside.
The other survivor was the paladin who was forced to kill his comrades in the armory. While the conjuring of the eye, he managed to submerge in the liquid. He woke up in the small room where the liquid had cut through the rock. There he heard the end of his comrades. But his fear and shame was too great to come out to fight or to flee. At some point he became very thirsty, but the disgust for the liquid kept him off (he saw the blood of his friends in it). Finally, dehydrated, he closed his eyes and didn't open them again. Maybe his ghost stayed in this place?