As Kalla talked, her body constantly shifted from a normal appearance to a skeletal figure enveloped in living shadows, very similar to what happened in her Wraith form.

"I didn't choose this form to be pleasant to the eye, nor to make friends." She explained once she noticed Lith's surprise. "It's just that being a giant bear makes it really hard to work with little things and I can't use spirit magic in front of humans."

"Have you discovered anything with Invigoration that we can use to develop a cure?" Lith asked.

"Yes and no. You'll understand once you see one of the infected. Is Solus with you?"

Lith showed her his right hand, where a stone ring was wrapped around the cloaking device Solus had forgemastered to hide her existence.

"Excellent move. I couldn't even perceive her even from this close. Nice to meet you Solus. I hope one day you'll show our human form to me as well." Kalla said.

"Just come visit me once." Solus used air magic to speak to her friend. "I've invited you to the tower more than once."

"I know." She sighed. "My children always rebuke me for my long absences, but my research is too important. If not for the crisis at hand, I would have not left my lab."

"I would have never thought that you cared so much for the human world." Lith was surprised by Kalla's words.

"I don't. You are misunderstanding my words. Undead plants are much more dangerous than normal undead. No matter if they feed on regular humans or beasts, their victims always have the opportunity to call for help or to band together to better defend themselves.

"In the case of undead feeding on plants, their victims are sitting ducks. Entire regions might be infested with undead and no one would notice until it is too late. Without the green, herbivores would starve and once they fall, everyone else will follow."

The tree hosting the labs was bigger than the White Griffon hospital, forcing the two Awakened to take a walk to reach the stairs for the lower floors. Lith noticed immediately that the underground facility was made entirely of rock and enchanted with an earth blocking array.

"Here we keep the patients that are willing to be cured, no matter the cost." Kalla explained. "Rock to prevent them to feed on the nutrients of the soil and the array to stop them from escape with earth magic once starvation kicks in."

Everything from the bare stone corridors to the thick metal doors made the place look more like a prison rather than a hospital ward. Kalla led Lith to one of the cells, showing him the enchanted padlock and the sequence of runes necessary to open it.

Inside, there was a Treantling, a tree who had gained sentience. Lith had no idea if plant folks had a gender or if it was just a matter of how they choose to appear, but it looked like a male to him.

Even though the Treantling was curled up in a corner of his cell, hugging his knees close to his chest, he was still over 1.5 meters (5') tall. His wooden limbs were as thin as a walking cane and the pile of leaves that covered the cell's floor once belonged to his now bald head.

The bark of the Treantling was nothing like the sample Lith had seen upstairs. It was of a dull black, creaking every time the plant folk moved. The creature's eyes were two black holes lit by a fierce red light that proved how the hunger of the symbiote was consuming its host.

The creature snarled at their entrance, yet he didn't move. Their stench was so disgusting that the Treantling was able to suppress his violent instincts.

'This is interesting.' Solus thought. Metal doors and walls didn't impede her mystical senses, so she had taken a good look at all the inmates before sharing with Lith her findings.

'Just as I expected, this Treantling has a blood core along with his mana core. Marth's therapy works because a weakened blood core can be easily destroyed by darkness magic but the resulting pain is inhumane.

'Also, for such a method to work, the body must be so weakened that it can't supply the blood core with energy any more. I'm afraid that not even all plant folks can survive this method, let alone humans.'

'You said this was interesting. So far the situation is just desperate.' Lith replied.

'Let me finish. Their situation is completely different from the undead thrall we met in Othre. Count Xolver had a blood core that was near his mana core and they were both made out of his own energy.

'The patients here, instead, have a blood core as well, but it doesn't show any sign of attempting to merge with the mana core. What's even more unsettling, is that the energy signature of the two cores doesn't match.

'Quite the contrary. Each infected has their own energy signature, whereas the blood cores bear the same energy signature, as if they all belong to the same person.'

Lith used both Invigoration and the tier five spell Scanner on the Treantling to double-check Solus's findings.

'What the heck?' Lith's exams proved that she was right, except for one thing. According to Scanner, there was no such thing as two Life Forces, only one.

After closing the cell door and Hushing the zone, Lith shared with Kalla everything he and Solus had found.

"Interesting." Kalla said. "My readings match yours, yet Solus's makes much more sense. During my time here, I used Invigoration to check both our patients and those who refuse to be cured.

"No matter how much they feed, they never turned into proper undead but remained hybrids. The only ones who actually became undead are those who willingly joined Erlik's ranks."

"I'm sorry, but you've lost me after 'more sense'." Lith admitted.

"What I'm trying to say, is that the plague is actually undead tissues that bond to their victims like a parasite and then spread to the rest of their bodies. The infected are not really undead.

"They are simply invigorated by the parasite who shares with them both its strength and hunger. Hence no matter if they choose to feed like undead or not, the parasite can only grow up to a certain extent without killing their hosts.

"They are not really hybrids so much as two different living beings almost fused together. We failed to realize it because whoever created this parasite engineered it so that the second life force would always be eclipsed by that of its host."

"Does this knowledge help you in finding a cure?" Lith asked.

"No, but it's a start. At least now I know why all of my experiments so far failed. It's because they were based on the wrong assumption that the undead matter was part of the patient, while it's actually a foreign organism."

Kalla sighed deeply and her whole figure turned to a shadowed skeleton for a split-second.

"Poor Nyka. She really hoped to become able to remain awake during the day. Yet if my hypothesis is right, whoever created the plague didn't make it to create hybrids, but only to use it as a ruse to push the inhabitants of Laruel on Erlik's side."

"And no hybrids mean that you can't apply it to your daughter." Lith completed the phrase for her.