The vastness of the underground ruins could not be seen but only explored to find out.
Ruins of a once majestic city lie in rubbles and debris before him while the giant frames and pillars of their damaged buildings still stood, rusted, deformed, but very much strong as it held up the ceiling.
Even so, these building frames and pillars appeared unnaturally welded together, forming a dome that protected what's left of the ruined city from the masses of land above it.
Leon discovered the scars of battle everywhere he looked.
From the top of the buildings to the ground below, remains of demons and humans lay scattered across the place, whether they were preserved or decayed.
"So this is the underground ruins… It's no doubt, a buried land of treasures," Leon muttered while studying the place.
However, the unnatural form of the building frames and pillars welded together concerned him.
'Were there survivors in this city, Tak-si?' he inquired.
'During the eruption of the Eternal Night Demon Empress's inner world, yes, of course, Master. Thanks to the Celestials' protection, there were still many survivors during that time,' the realm spirit replied.
'Then where are they now?' Leon inquired further.
'Well, that… they're all dead now,' the realm spirit said.
'Even though the Eternal Night Demon Empress's inner world eruption brought the battle between the Celestial Alliance and her faction to an end, it wasn't a conclusive one.'
'The Celestials all fled in fear of the Eternal Night Demon Empress's dark power's corruption while those who got trapped and left behind all died to the dark energy eventually.'
'Only the creatures of darkness have no problem living in such an enclosed world overflowing with dark energy, Master,' the realm spirit explained.
'You should have just said that first instead of saying there were still survivors,' Leon replied with a shrug before landing on the solid ground.
Shortly after looking around for a bit, he asked, 'Where's the core?'
'The core is just a straight road to your left side, Master. It's not hidden, so you will know when you see it," Tak-si answered.
'Straightforward enough,' Leon nodded.
In the next moment, he immediately took in the left direction with a burst of speed, moving swiftly to reach the core in the quickest time possible.
Myriads of treasures lay scattered on the ground, but he ignored everything and headed straight for the realmship's core.
It wasn't too late to pick the treasures up on his way back or another time; binding the realmship's core comes first and foremost.
Swoosh—!
Leon's figure shot past piles of ruins quickly, making them look like blurred afterimages while kicking up a trail of wind behind him.
Grrrr!
However, the sudden growl of a ghoul immediately made him come to an abrupt stop to look before he discovered most of the decayed corpses on the ground began to move.
The least decayed corpses were ghouls in the truest sense, while the most decayed corpses were simply undead skeletons.
Nevertheless, they were all awakened by Leon's presence and vibrant vitality.
'I thought you said there were no survivors?'
Leon frowned while watching the number of ghouls and undead gathered in large numbers, almost nearing the thousands and still growing.
Given the size of the ruined city, there were bound to be at least millions of corpses.
'Can these ghouls and undead skeletons be considered survivors, Master?' Tak-si replied wryly before adding, 'Given Master's strength, these ghouls and undead skeletons pose no threat to you.'
Leon's lips twitched.
While most of the ghouls and undead skeletons were weak, some among them were also close to the Arch Demon level.
Their strength might not be at that level, but their bodily defense was at least at that level.
'These weak mobs don't bother; what does, though, is that there are plenty of Celestial corpses in this underground ruin! Are you trying to screw me over?!' Leon accused the realm spirit.
He should have known that given such overflowing dark energy in the secret realm, it would have given birth to ghouls and other forms of undead beings.
'Definitely not, Master!' Tak-si denied.
The realm spirit had no reason to kill the only person who could repair it. On the contrary, it ought to protect Leon at all costs instead.
'You don't need to worry about the Celestial-level ghouls and undead beings, Master. Celestials can't be influenced by the dark and deathly energy in this space and become undead beings.'
'Oh? Why not?' Leon furrowed his brows.
After hearing the realm spirit's explanation, he had quickly formulated his guesses. Still, he wanted to confirm it from the realm spirit's words.
'Celestial bodies are reforged to cultivate celestial energy that comes from the stars, making them extremely yang in nature, which is very conflicting with Eternal Night Demon Empress's dark energy.'
'As such, evil spirits cannot possess such the Celestial bodies; they will only clash and die inside the Celestial bodies if they attempt to,' The realm spirit explained.
'The reason turns out to be like this after all, huh?' Leon mused before his flickered sharply in the next moment.
Smoosh—!
The Tier-7 White Spear quickly appeared in his grip before he cleaved his way through the army of ghouls and skeletons obstructing his way.
Overlord Spear Art's Second Spear – Spear Vanquishing the Demons!
Hundreds of ghouls and skeletons were immediately cleaved away by his Tier-7 White Spear infused in his dark energy.
Then, he continued to rush forward, whether he had to cut down the undead beings or leap right over them.
'I don't have time to waste on these ghouls and skeletons; I'll just head straight for the core,' he silently decided.
Sometime later, the spherical-shaped core, which was nearly the same size as the support-circuit buildings, came into sight.
Leon immediately darted towards it while being chased by an angry undead mob numbering in the several tens of thousands behind him.
After entering the core, his eyes quickly fell on the realm spirit's heart, an enormous divine crystal many times bigger than the divine crystals found in the other support-circuit buildings.
Nevertheless, put aside its size, his eyes focused on the beautiful girl sleeping inside of it.
She shared a resemblance to the Eternal Night Demon Empress, but it was no doubt her daughter's true body.