Quylla followed the life force's movements throughout the tree's huge body, dwelling mostly on the sacks of corrupted life force and the areas affected by the mold. Quylla knew nothing about gardening, but as a Healer, she could understand an illness just by looking at the effects it had on her patient.

Leannan was itching with curiosity, wondering why she didn't feel anything amiss during her first visit after Erlik's escape and why her mystical senses were still unable to sense her subject's suffering.

'I could temporarily merge with the tree to understand what's happening or examine the mold, but I can't risk interfering with the little Ernas's work.' She thought. 'My link with the World Sapling might enhance the treehouse healing factor and erase all traces of Erlik's experiment.'

Time passed, and when Quylla's consciousness returned to the roots, she followed them and went deep underground. Lith had been forced to stop at that point, the mass of life force was too great and complex to follow it by using means devised to study humans.

Quylla, instead, had adapted Scanner to make it work on plant folk, so when the interference assaulted her senses, she was able to shield her mind and continue following the treehouse's lifeforce.

"What the heck?" Quylla suddenly snapped out of her spell. Her face turned pale while huge droplets of cold sweat quickly appeared on her face.

"What's wrong?" Lith had been on guard the whole time, yet he had no idea what could scare her so badly.

"There's something down here. A creature so powerful that barely approaching its consciousness almost damaged my mind."

'How can a human reach out to the Sapling?' Leannan was shocked. No one could interact with the plant folk's ancestor without their existence being acknowledged by them and being bestowed the runes that adorned her shoulders.

"That's it? It must be the World Sapling that fuels the treehouses." Friya's sighed in relief, giving Leannan the plant equivalent of a heart attack.

"How do you know about the Sapling?" She asked. Its existence was supposed to be kept a secret from outsiders. The edge on her tone let the group understand that she suspected them to be spies.

Not wanting to cause a diplomatic incident, they told her the full story about their fight with the Grendel's thrall, including its aftermath.

'By the Great Mother, my subjects are a bunch of morons!' Leannan suddenly didn't consider keeping the plant folk isolated from the outside world a good thing anymore.

'They are so used to freely talk about everything that they spilled the beans with humans just to satisfy their urge to mate. So much for Laruel's secret. The silver lining is that it will make explaining things easier.'

"It might be, but that's not all." Quylla was eager to finish her report before the details of the impressions she had experienced while using Scanner faded away in her memory.

"There's one more sack of life force between the creature and the treehouse. Yet this isn't just the tree's own life force twisted beyond recognition, it belongs to an undead energy signature."

'Solus?' Lith asked while his partner used her mana sense to probe the ground below them.

'Sorry, there are too many interferences. I can't tell you if the energy signature of the undead sack and that of the parasite match.'

To Leannan's ears, Quylla's words were as scary as they didn't make sense.

No one besides Laruel's ruler was supposed to be able to perceive the Sapling's energy since even though the entire city was actually grown upon the roots of the ancient tree, Laruel and the Sapling were still two separate entities.

The World Sapling was long since in a deep slumber, trying to prolong its existence and find a way to escape its inevitable death. The magically engraved runes on her body were supposed to be the only way to draw the Sapling's consciousness and call upon its power.

Yet a simple human claimed to have accomplished it on her own. A terrible picture appeared in Leannan's mind as finally everything started to make sense. She scratched a bit of mold from the treehouse's roots, lowering her defenses to allow it to invade her body as well.

She was shocked seeing how quickly it spread from her nail to her hand, covering it in a matter of seconds. On top of that, the mold didn't just rob the Titania of her nutrients, it also started to attack her life force and converted her flesh into its own.

"This is impossible." Leannan blurted out. "The mold is capable of overtaking its host life force, not just sucking it. It means that if it's not stopped in time, the victim gets turned from their original race into mold."

The contradiction in her words was apparent even to Phloria, who was just a junior Healer, yet no matter what the academy had taught them, no one could deny what they were watching with their own eyes.

Leannan's hand had not shapeshifted, it had been entirely replaced by the mold while retaining its appearance while the infection spread to her forearm. The Titania snarled and stopped suppressing her strength.

Both her life force and her body were too powerful for the flimsy mold, which was eradicated in a matter of seconds.

"This is terrifying." Quylla said. "Life force can be stolen or shared with spells, but it always goes from one recipient to another while shielded by darkness magic, so that the two energy signatures never interact.

"Otherwise the stronger life force would completely assimilate the weaker, making the healing impossible."

"Somehow, this mold is able to open a channel to its host's life force while also preventing it to swallow the mold's. I could feel my hand being ripped apart piece by piece as if it was being constantly cut and sewn back together." Leannan said.

She immediately called the Healers, tasking them to retrieve samples of the foreign organism to study it. Yet as soon as the mold was without a host, it died. They tried to cut it away with part of the treehouse, but it died again.

"Dammit. Whoever designed it, used plant folk's physiology against us. The piece of treehouse dies almost immediately after being cut away from the main body since its vitality is already compromised after being affected by the mold for so long.

"The only way to sample it, is to give it a live host." Leannan tried to have the mold move on regular plants or small animals, but to no avail.

"I think I know what's happening here." Quylla said, giving Leannan the second heart attack of her long life.

"Erlik has infected the tree with the mold because thanks to its abilities, it weakened the plant's life force enough to apply the Body Sculpting devices. As you said, plant folk's life force regenerates quickly, so without the mold, the devices wouldn't have worked.

"Then, for some reason that I can't explain…" Leannan inwardly sighed in relief.

"They repeated the operation on the upper floors. I don't get what their aim was, but I'm sure that they didn't mean to kill the treehouse. It would have been pointless since the tree's bad shape was bound to give away their position.

"Also, they didn't want to create the sacks of life force either." Quylla said