The energy seeped into the ground, and countless skeletons, both human and animal, emerged from below. Their mouths were agape in a silent scream, fighting their way out of mud and roots.

Several hands grabbed Lith's feet and ankles with an iron grip. In a few seconds he was surrounded by a small army of undead, each emitting an ominous aura that sent a cold shiver down his spine.

Lith knew they posed no threat to him. A single lesser undead was nothing more than an annoyance, even that many couldn't harm someone like him. Worst case scenario, he would simply take off and attack them from the sky, leaving them no possibility for retaliation.

But his body seemed to ignore all that knowledge. The only things he felt from their shiny red eyes were innate fear and revulsion.

He kept his cool, keeping those emotions sealed in a corner of his mind, while exploiting that contact to use Invigoration on them and understand how did Kalla manage to do it.

Lith discovered that each of the skeletons grabbing him had now a small red mana core.

Invisibles to the naked eye, countless tendrils of energy departed from it, keeping all the bones together and allowing them to move and feel. Unlike normal cores, though, they had black stripes, pulsing and growing every time the undead moved.

"In this world the dead outnumber the living by hundreds. An expert Byk will bury its preys and turn them into a weapon. The shock they cause and the sheer numbers can easily turn tables, if properly used."

With another tap of her paw, the skeletons crawled back underground, and through her use of earth magic, no trace of their passage remained.

"Necromancy can be roughly divided in two branches: lesser and higher.

Lesser necromancy, which I just used, allows to temporary turn any corpse into an undead. It doesn't require much energy, but the effects are short lasting, and its creations are incapable of thought, they can only obey simple orders.

Higher necromancy, that you foolishly attempted, though, is an entirely different matter."

With a flick of her snout, Kalla conjured near her the ashes of the Lith's monster, stirring them with a darkness imbued claw, biting her own other paw to let some blood drip on them.

Horror struck Lith when he saw the ashes turn into a semi liquid state, coiling around the claw and using it to stretch closer to the blood source.

"That thing is still alive?" He unconsciously took a step back.

"No. I'm just playing with the residual energies, just to show you how powerful necromancy is." As soon the Byk stopped infusing dark energy, the blob turned back to ashes, despite the blood still dripping on it.

"Higher necromancy allows to create lesser undead capable of lasting forever, or even superior creatures, capable of independent thought. Yet no matter what you do, higher necromancy has a flaw compared to the lesser branch.

After I called back my spell, the skeletons were still intact, and if I or anyone else were to raise them again, they would still serve their master. The same would have happened if I kept them around until the spell wore off.

But when something is created out of higher necromancy, the unbalance is too severe.

If the caster doesn't feed his creatures with the proper amount of light energy, the dark magic that animates them starts to corrode their bodies, until they turn into dust."

The Byk sighed sadly.

"I tried countless times, but my inability to use light magic prevents me from truly mastering necromancy. All my creations have the lifespan of a butterfly. Undeath is no life, to sustain it a price has to be paid.

The better the necromancer, the less energy the creatures require. But no matter how little it can be, raising a permanent army would either drain the caster or require an external source."

"Do you mean taking lives?"

Kalla nodded.

"Skeletons are simple, they require raw energy, it's irrelevant to them the source it comes from. Other creatures can be pickier, and require living flesh or blood to sustain their existence if the necromancer's energy is not available.

And that usually means that lots of people have to die."

"Wait, are you telling me that an undead army has to 'eat' regularly? Isn't that a contradiction?"

"Contradiction?" Kalla snorted. "Have you ever found anything, alive or not that moves without needing energy? Humans need to eat, and so do plants. For a stone to roll, someone has to push it.

Or else both humans and magical beasts would only fight with undeads. Imagine an army that does not rest, eat or fear, that grows in number with every battle. No, Scourge, that would be nonsense."

- "Kalla is right, otherwise necromancy would ignore the first law of thermodynamics, energy cannot be created or destroyed. Only be transferred or changed from one form to another. But that poses another question.

Then how can magical objects never run out of juice? What is their energy source?"

"The magician." Solus observed. "That must be the reason why the imprinting process is necessary before using one. Is not only a safety measure, but also a way to feed them. That would also explain why magical items can be reused after their master's death." –

"I have a question. According to what you say, undead should obey the necromancer. Why the creature attacked me?" Lith asked.

"As I said, I haven't mastered necromancy, yet. But the most likely explanation is that your clumsy spell didn't bear your mark with it. Because of that, it didn't recognize you as its master, but only as a prey.

Especially so if it hated you when it was still alive."

"What do you mean with mark?" Lith was clearly lost. "And why should a dead man feelings matter?"

Kalla snorted even harder, causing Nok to chuckle at his expenses.

"By the Great Mother, how could your parents let you walk alone in this world being so ignorant?" It said shaking its huge head in desperation.

"Based on what Nok told me, you used higher necromancy, turning someone that was still alive.

It wasn't a mindless corpse, but someone that died cursing you with his final breath. Even if your attempt failed, the creature was bound to carry with itself the deepest emotions linked to its death.

Not having a mark, its primary instinct was likely to exact revenge. Are you finally starting to understand the foolishness of your actions?"

Lith nodded, recognizing that being so powerful and yet so ignorant in the ways of magic was a terrible combination.

"Do you at least know how to raise a single undead?" She then asked.

"No. What happened earlier was an accident." Lith didn't like admitting his incompetence, but having worked in the science field, he knew that knowledge could not be faked. Either you accepted your ignorance, or studied to fill the gaps.

They walked up to Rodimas' corpse, then Kalla started explaining.

"If you were to simply use darkness magic on a corpse, it would rot and disappear. What you need to do, instead, is to let the necromantic energies fill the body or the skeleton, like this."

The Byk placed its claws on Rodimas' hollow forehead, while Lith used Invigoration to see the stale blood turning black because of the dark magic, the veins bulging out.

"Once it's saturated, add a speck of light magic, even first magic is fine. That will be your mark, the only life force the undead will respect and obey to."

Rodimas' corpse eyes opened again, the chestnut colour replaced by the bright red. Kalla was about to withdraw her energies, but Lith asked her to wait a bit. That way he was able to notice that the creature had no blood core, just a red one striped black like the skeletons did.