Demon Lord's Reincarnation

As the monster called Arthur continued to kill all in his way, the commanders of each battalion of soldiers from the different noble families had no choice, even if it will result in friendly fire, they needed to start to fire a barrage of spells on this monster. 

The stronger mages in the battalion started chanting, while they were doing so a lot of warriors protected them. They all risked their lives to protect the mages before they could cast their spells. 

Arthur in his berserk state did not dodge and simply took all the hits, but his bursting mana was helping him regenerate at an unbelievable pace. So most of his injuries even the fatal ones quickly healed. Not to mention it was very hard to actually harm Arthur, his body was sturdy and his burst of mana not only helps in regeneration but was creating a constant shield. 

Still, Arthur who has been constantly regenerating and fighting for half a day had depleted a large amount of his mana. Also, [The Berserkers Will] was a skill that will only disappear once his mana supply was nearly empty or if all within his sight was dead. So Arthur continued to roar as he crushed all in his way. 

...

The mages had finished chanting their spells. The moment they were done they unleashed a barrage of spells towards Arthur all of which were powerful fire spells. Seeing that among elemental magic fire spells had the most destructive power. 

The spells not only hit Arthur but every one near him. Still, those that were hit didn't blame their companions as this was the only way they could think of to stop the monster. The flames from the bombardment melted all that was in its path, the buildings, the ground, and all the soldiers. 

Seeing that it was a direct hit, the mages were about to sigh in relief when they still felt that overbearing bloodlust. They then saw within the flames were nothing else was alive, the boy was in the middle of it. Arthur's body was being scorched but because of his outburst of mana his burning body was able to regenerate quickly, and most of the attacks were blocked by his mana shield. 

Seeing that unbelievable sight, the mages were about to chant another spell when Arthur jumped in the middle of their group. He started ripping the mages to shreds. The unit tasked to protect the mages tried their very best to attract Arthur's attention and try to stall him as the mages get some distance. 

Almost half of the mages had been killed, but still, the remaining mages continued to chant their next spell. There were of course deserters that were lucky enough to escape, but those were few in number. The rest were trying their best to kill the monster before them. 

After a while, the mages were finally done chanting their next spell. If fire spells were ineffective how about ice spells? Ice spells were a difficult branch of water magic to master, but those that master them were able to cast very versatile spells. The next spell were three different spells. 

"[Frozen abyss]!" The area where Arthur was was frozen and even the flames that were covering the place disappeared. 

"[Ice Cage]" Thick layers of ice surrounded Arthur from all directions. He was trapped inside a cage of ice. 

"[Glacier Spike]" Numerous spikes of ice burst out of the ground killing everything in its way. 

...

When Reginald saw what happened and felt the diminishing mana fluctuation of Arthur's mana, he felt elated. He stood up and was about to congratulate the brave men who had killed the monster, when suddenly the diminishing mana coming from Arthur burst outward, with even greater strength. 

The field of ice was instantly destroyed and with it, most of the nearby soldiers fell as well. Arthur roared in anger as he charged and killed the remaining mages.

When Reginald saw this, the hope that rose up from his heart turned into deep despair. He was so deep into his own despair that he didn't notice that Arthur's mana had weakened significantly. 

...

In the sky above the city, a figure was watching the whole fight as it transpired. In the beginning, he was enjoying the massacre and despair, but as the fight continued he started frowning. 

'If he kills all of those that I have influenced, then it will be harder to gain more malice. Since a lot of us have escaped the seal, there's not much malice to go around. If I lose this area then a large chunk of my malice will be reduced.' The Primordial Demon flying in the sky was frustrated. 

Now that there were more of them out and about, they needed to share malice. So they gave themselves different areas to operate in. No one was allowed to absorb the malice of other areas. Now that his area was losing too much of his puppets that could spread more chaos, and give him more malice he decided to take action. 

"Sorry Kid, but even though you gave me lots of malice, seeing as I can't seem to influence you too much, I need to get rid of you." As the Primordial Demon was about to attack, he heard a voice that seems to be talking in his head. 

"Sorry, but you can't do that." The Primordial Demon finally noticed that someone was floating right in front of him. The man that suddenly appeared had a very vicious smile on his face. When the Primordial Demon saw that smile he was reminded of the person who sealed them in the cave. When the Primordial Demon thought of that he wanted to immediately flee, but unfortunately for him with his current power he wasn't able to do that. Ren had already grasped the Primordial Demon's neck. 

"It's a good thing I came. I kinda guessed that one of you guys were at the root of all this. So now that I met you I'm going to give you two choices. The first option is that I'll kill you both in body and in spirit, which I mean literally.. The second option is I just destroy your body, and I'll absorb your spirit into my soul. So what will it be?"