Her question reminded Eldrian of the Night Terror he and Vivian had faces. Causing him to shiver, hoping that they would not suddenly appear here. It was one of the strongest monsters he had faced thus far.

While the undead were not easy to kill, they at least had weaknesses. The Night Terror seemed to have none, at least none that could weaken and contain it. The only thing better about the Night Terror was that it did not smell.

After that flashed in his mind, he then recalled the fires that were used to keep them at bay. "Something to do with fires that the priests bless."

"Correct, that is what the chanting was for. To give the pillar some divine mana, similar to how they blessed the fires. The array takes that as a blueprint for what it will send out."

"So... The area inside the pillars will be filled with divine magic?" Eldrian asked, wondering if this was even possible.

"Not quite, that is a bit too hard to do." Eldrian didn't follow and made it clear to Thesolis, who then continued. "If that was possible, not only would undead be weakened, we would also be strengthened. The very air would heal us if that was the case."

"Then..."

"The array we are going to carve will use the divine mana to detect the undead. At the same time, it will also target the undead, releasing Divine Cleanse on it. It should kill most weaker undead outright."

"That sounds even better," Eldrian commented, Thesolis not knowing if she should laugh or sigh at his ignorance.

"It isn't. It costs a great deal of mana and there is no way to tell the array to only target higher undead, who are the real problem. An entire Mov Crystal will be used up after killing around 8000 undead."

"That's amazing!" Eldrian exclaimed, only to find again that this seemed to not be the general consensus.

"No, it is not. Unlike mana crystals, Mov Crystals cannot recharge. Hence each is extremely rare and costs at least a 1000 gold."

Eldrian gulped upon hearing this. Unable to accept this so easily. "Why can't you make the array target specific undead? Can't you use the difference in strength to determine who is a threat?"

"If it was that easy we would do it," Thesolis replied shortly, irritated by Eldrian's assumptions. "Do you know how hard it is to find an undead's strength, based only on the reaction divine mana gives to the present of undeath?"

"It is not like all strong undead will cause a greater reaction. Some can almost completely hide their nature. It is why we always use Observe to confirm their strength, we can't judge them properly otherwise."

"For example, the worst undead for this array is a ghoul. The weakest ghoul will give the reaction of a lower undead, while the stronger ones would appear to be a newly created Tier 1 lower undead."

Eldrian did not reply, instead, he just nodded. Not having known that the undead could hide their aura of undeath had caused him to just assume things. Still, he felt there must be a way.

If that is the case... I wonder if it is possible to make an array for Observe. But... There must be a reason why they do not do this.

The rest of the way they walked in silence. Arriving at a new marble pillar which two centaurs were busy planting in the ground.

"Orelis, Therios." Thesolis nodded in greeting, looking at the pillar they were installing. "Where is the rest of your group?"

"Undead." One of the centaurs answered, "Thesolis, please make sure the pillar isn't damaged. We had to retreat in haste."

Thesolis nodded and inspected the part still above ground, the two lifting it up so she could also see some of the buried part. After finding nothing wrong, she nodded to the two and they continued to install it.

"Do you know what arrays are?" Thesolis asked Eldrian as they waited for the two to finish.

"Kind of, I mean they are like static spells. Right?"

"Yes... And no. They aren't necessarily static, nor are they spells. They are arrays, a way of manipulating mana far past the limit of normal mages."

"A spell is just manipulating mana, so doesn't that mean they are indeed spells?" Eldrian countered, for once not receiving a sigh in return.

"If that is your definition of a spell, then you are right. Most, however, do not see spells like that."

Eldrian shrugged hearing this, he knew his way of understanding magic differed from most.

"Do you know how arrays work?" Thesolis asked after a slight moment of silence, the two centaurs finishing the implanting of the pillar and heading to the camp to get a priest.

"Not really... They are similar to spell modules but more complex. For some reason you guys also gave the nodes and pathways different names. But they function the same, right?"

"Correct on the first part, not the latter. With a spell module, the nodes are the entry and exit points for mana. However, with an array, it is the convergence point and hence its name. The mana supplied to the array start here, always."

"After converging at all the convergents, the mana then flows through the Rilpai. The patterns we carve. It flows instantly and has the same amount of mana everywhere. It is not like water, instead, it appears to just instantly appear once activated."

Sounds like electricity, Eldrian thought.

"As such, the longer you make a Rilpai, the weaker its effect. At the same time, the shorter it is the less distance the mana it releases can cover. Thus the smaller the effect of the array."

"That is why we have these pillars." Thesolis patted the pillar, which was over two meters tall after being installed. "We want a large coverage, more as a warning for us than for a defensive array."

"The larger covered area means the spell we imbue in it has to be weaker, however, thanks to Pelaros supplying us with a Mov Crytal, the spell will still be Tier 5."

Eldrian nodded and then asked, "Are all the patterns you carved in the other pillar one array?"

"Gods no... That would be beyond insanity. In that pillar, we carved four inner protii and one outer."

Eldrian looked at her in confusion until she continued.

"Arrays are not set in stone. Unlike spell modules, their patterns can be adapted and changed. The effect will change, and it might even fail. However, what works and what does not has already been experimented through the years."

"That is part of the reason why we have someone casting the spells into the pillar. It allows the array to function properly even if the pattern does not match."

"As for what protii are, you can consider each one an array. Inner proto are generally smaller arrays, however, they can be just as complex or even more so than the outer proto. In our case, this is actually what is going on."

"The outer proto is a detect array, sending out a bit of mana in a large area every second. This is what drains the mana crystals. The inner protii, instead, are the spells we decided on using to kill the undead."

"Divine Cleanse is the first. This is the pattern for it." Thesolis said, drawing a complex pattern on the ground. If Eldrian didn't know better he would assume it was a spell module in the shape of spiraling winds captured inside a circle.

He knew that Thesolis had just drawn the pattern, the actual array having much more added. The things that made the lines Rilpai and not pathways.

"This spell should kill most lower undead, as it fills them with divine mana." Thesolis stopped, not knowing how to explain how it worked, but Eldrian had an idea and seeing her hesitation he voiced it.

"Like how Thera also works against the undead?"

"Yes. But far more efficient. Nature magic spreads its energy over all of the undead, trying to heal it to its original form. The mana sustaining its undeath fights this. And the resulting fight is what causes damage."

"Divine magic instead directly changes the undead parts into living again as it passes through. Causing the undead massive pain and costing far more mana for it to repair. Generally what happens is the two override each other and the affected parts turn to ash."

Eldrian nodded, finally understanding why divine magic did more damage. However, he did not quite understand how this all worked. Especially what it meant to turn the undead parts into living parts.

Still, he kept quiet and let her continue to explain, "The next spell is Smite. Unlike Divine Cleanse, smite focused all its power on one part of the undead. The spell can take on many different forms, the most common being a sword or hammer."

"Can you show me?" Eldrian asked, having never seen weapons being materialized by magic.

"No, I can't use divine magic." Thesolis replied while shaking her head, "However it is less effective than you might be imagining. Normally the form will be smaller than real weapons, often only as big as your hand or arm."

"Ohh..." Eldrian lost all interest upon hearing this. Letting Thesolis continue her explanation.

Divine Cleanse wasn't a targetted spell, the energy was just sent to the target like the Anthos spells. Smite instead was more like a Frost Needle, however, most people couldn't control it. Hence they aimed and let loose.

As Thesolis explained it, the damage was nearly twice that of Divine Smite. However, it would only damage the part that was hit. Meaning if the target dodged, then it does no damage.

"That is why Divine Cleanse is used first. It should weaken and slow the undead. If the array detects it did not die, Smite will be cast near it. Giving it as little time as possible to react."