A/N: Youkousho mina. We are back to Caster of Death. Lately, there has been no action, hasn't it? Well, Fate/Zero and Overlord do not have much action themselves, but the banquet of kings will finally happen. Well, without further ado, let's go.

There's a canon scene here, but it will be quite different since I do not remember it quite well.

Proofread by Thatguywhowrote.

-II—II-

Meanwhile at the factory which had been converted into a temporary base, the Overlord of Death along with his two familiars and master were currently residing. After a new member joined Ainz' rank as another familiar, he had been thinking about what to do with him. He still had not yet grasped how his summoning became weird and ended up calling a different entity than the one he had intended.

Ainz knew his identity was Hassan I sabbah, also known as the Old Man of the Mountain and whose name gave birth to the word "assassin." Ainz grew curious at how Azrael could be related to a legendary assassin.

"How shall I address you, by the way?" He tried to strike up a conversation with the death knight assassin.

"Assassin shall suffice, or by any name thee wishes to call me. However I must ask, thou art not a master yet thine presence feels as if thou art not a servant. 'tis like thine hath been summoned at full power." Hassan spoke, observing Ainz carefully.

"What do you mean? Can you elaborate?" He was surprised at his question. He had the presence of a servant and yet there was something else different? It was as if he was summoned at full power?

"Thine presence is similar to a servant, yet something is amiss. Even I who hath been summoned by you, feel different. I hath been called only as a familiar, not as servant. but I feel my power more than a match to those of other servants. I also believe there is still one slot open in the grail, and your presence can fill that."

"Empty slot? Fill that up?" Ainz pondered, trying to comprehend his words. Even Jack herself had no idea at what he was talking about. How did Hassan know all these?

"Does thou not understand, o Bearer of Death? Thou art not fully a servant, there must be a mistake in your summoning, or maybe thou used a different ritual than the grail. And that empty slot had not yet been taken. I will not be surprised if there is another Caster." Ainz was even more surprised. Another servant besides him?

"Thou must be thinking how I know of this. Simple, I know far more about this grail than the regular servants whom have been given only basic information. I am the last defense mechanism against the extinction, I am formerly known as the Grand Servant, the Grand Assassin, though I have already abandoned that title. And this grail pales in comparison to the counterforce. Even if I no longer am one of the Grand Servants, the knowledge still resides within me." Hassan explained.

'Grand servant? What does that mean, that he's far superior in power than the others?'

"But I ought to tell thee..." Hassan spoke again while Ainz was still pondering. "...beware of Gaia and Alaya, they are still confused at what thou art and how doth thou exists. They might not yet make a move and that must have something to do with the Root. But even I as the Grand Servant cannot comprehend how your summoning relates to Root since it is outside my scope of knowledge."

"Root? You mean the Root of All Knowledge, Akasha?" Ainz asked Hassan but as he had said it himself, he knew nothing of it.

"Isn't there something more important thou hath to do? Such as finding the perpetrator thou spoke of before? Thou has no need of that fake wish-granting device of blasphemy, you should strive for thine desires. Those are the teachings of the God, it is not worth the time to seek some empty cup." Hassan said while seemingly reminiscing something.

"You're right. I have no wish that needs to be granted. Then I shall deploy Eight-Edge Assassins to find a lead on that woman. Anyway, my bone vulture has not yet returned, I wonder what happened..." As he contacted his summon, his skull suddenly began ringing with a notification.

It was a doll that he gave to Irisviel, the master of Saber. If she broke the doll, it meant Irisviel needed something from him. He needed to check it out.

"Hassan, from now on I will call you Azrael to avoid the enemies from knowing your identity. And Jack, your name would be Jane. Ryuunosuke, I want you to stay away." The two familiars nodded while Ryuunosuke simply shrugged.

"Well, whatever. Thanks for the toy, my Lord! I might want to test it out for my next project. Have fun!" He said before leaving the building.

"Then let's go, Azrael, Jane. We will use my [Gate] spell." The three entered a dark portal that Ainz opened, closing behind them once they all passed through it.

-II—II-

Meanwhile, before Irisviel broke the doll...

'This is bad, totally bad! How can Kirei be here?' Thought Irisviel von Einzbern after seeing the former executioner before her.

"So, you're that homunculus? Where is Kiritsugu? I believe he should be near." Asked Kirei, Maiya tried to protect her by standing in front of her.

It's bad, Kiritsugu still fighting archibald and Saber still trying to fight Lancer in Honorable battle. There is only two of us here.

She couldn't let Kirei meet Kiritsugu no matter what, but he was a former Executioner. How could the both of them stand against to those who trained to fight with the Dead Apostle? Maiya might have a chance in close range combat. but the white haired woman only knew healing magecraft and forging matter to string. Kirei was known to be a close-range combatant as far as Kiritsugu informed her.

There was a low, or even no chance that she could fight Kirei if he was too close. His reinforcement and cloth could render conventional weaponry useless, Maiya would be at a disadvantage.

"Lady Irisviel! Please run while I stall for time!" Maiya held her knife at the ready. She was about to fight Kirei in close combat which was tantamount to suicide. But Irisviel couldn't leave her alone, even if she hated her for doing this she couldn't let her.

She prepared her string created from mana. Maiya, seeing there was no other choice but to accept her help since it was unlikely she could beat Kirei alone, let her be.

Kirei wielded sharp weapons in both hands known as the Black Keys, the main weapons of an executioner. It had the ability to create abnormal phenomena such as immobilizing movement by piercing its victim's shadow.

Maiya was aware that Kirei was an expert in handling that church weapon, she had to approach him to get close enough to pierce him with the knife. Black Keys did not work well against daggers or short knives due to unbalanced fighting style.

But, it was no easy feat since Kirei is very fast. When Maiya tried to near him, Kirei suddenly dashed with reinforcement and stopped right in front of her, catching her unexpected with his speed.

His Black Keys were ready to pierce the surprised Maiya, but luckily the white homunculus used her string to bind Kirei to a tree with a strong formation. Kirei couldn't move and his weapons fell to his side. This was Maiya's chance, she dashed to stab Kirei but before she could deliver the blow a dagger flew towards her direction at incomprehensible speed. It hit her stomach, stopping her movement and falling on the ground.

As Irisviel rushed to her aid, she found that what struck her was a dirk, which only meant one person who was responsible.

It was an Assassin, with a white mask that only the Old Man of the Mountain wore, that appeared before them. Kiritsugu already informed them that Assassin was not yet dead, and it only served to make matters worse.

He swung his weapon at her which she dodged, but the attack was aimed at the string which she bound Kirei with. Using his impressive strength he broke free from the loosened shackles. There was no way they could escape, she was also worried about Maiya's condition so she tried using her healing from afar.

Kirei then grabbed Maiya by the neck and pulled her away, stabbing her with his Black Keys. Her groan of pain made the white-haired mother's emotions overcome her logical thinking and she rushed to her side.

Anticipating this Assassin threw his dirk and hit her foot, she didn't even have time to react as it was too fast for her. Once Kirei was done with Maiya he finally approached her, lifting her up by the neck. She choked on his grip, which was strong enough to bend metal beams.

"Tell me, what is Kiritsugu's wish?" Irisviel couldn't understand his question. And yet his eyes told her something. They were the eyes of one who sought purpose, eyes so dark and hollow as if it were an endless void.

"If you don't wish to talk, maybe I should make them let you." He said without emotion while preparing his weapon to pierce her. As she struggled, Irisviel remembered something.

'What is this?' She was at the dock then.

'It's a means for communication. If you want to meet me or need my help, break that doll and I shall depart to your position.' He explained before he vanished into thin air.

Irisviel tried to reach for her pocket and grab a certain doll made of clay to crush it in her hand. Kirei saw this but paid no heed and aimed his weapon to strike her, interrogating her before going to kill her. He kept asking about what Kiritsugu wish and such, to which Einzbern replied.

"His wish is the most beautiful wish anyone has ever dreamed. It's so distant, and yet he still tries to reach for it. It's impossible, yet he tries to make it possible. It is not something what you expect to be." Kirei contemplated on her words before finally stabbing her in the stomach and leaving her to die.

He was very dissatisfied, the answer he sought was not what he had expected. But then, another Assassin beside the first one that help him appeared and informed him something.

"Master, Saber will come. We must leave immediately to avoid confrontation." He said, which made Kirei nod and begin to leave. But as they turned a dark portal appeared before him, and from it exited three individuals that Kirei knew one of.

It was Caster.

-II—II-

'What's happening here?' Ainz thought, seeing the seemingly dying Irisviel and a woman he didn't know off. It seemed she had called him for assistance. Well, he did tell that to her before, but where was Saber? And who was this man? Noticing the masked person beside him, Ainz could deduce who he was due to his presence.

It was a servant, and Ainz remembered that he was the one he saw at the dock before. It should be Assassin, but enough about that. Saber's master was dying and if he let her, Saber would vanish along with her Excalibur. There was no time to waste.

"Azrael, can you take care of the servant?"

"...Hmm, worry not. I shall dispose of him." Said the first Assassin, materializing his blade with blue flames and slowly approaching the slim-built Assassins. They saw this and began to escape towards the forest to blend in with nature. Hassan then summoning flames to surround his body and vanished without a trace.

"Jane, please take care the human. It should be an easy task for you." Ainz ordered, Jack nodded in understanding and materialized her revealing clothes for battle and prepared her dagger. Kirei, noticing the hostility from Jack, readied his Black keys. Although he didn't know who this girl was, one thing was for sure. She was not one to be taken lightly.

Kirei couldn't let Caster heal Kiritsugu's spouse and tried to intervene, yet Jack intercepted him first before he could even move from his position. He nearly couldn't react due to her speed and barely blocked her attack. Her strength was also impressive as she managed to overpower him even though Kirei already used reinforcement.

'It's almost like fighting a servant,' though Kirei, experience her fighting prowess.

While he was still busy fighting the familiar, Ainz already approached Irisviel and Maiya who were both on the verge of death.

"...such pitiful states. To think you were beaten badly by an enemy master." He said while eyeing her. He was about to do something when Saber appeared from the rear and suddenly threw gusts at his direction. It was Strike Air, a wind force capable of blowing away multiple large trees.

But Ainz anticipated this and his High Tier magic invalidation began protecting him. Strike Air didn't even touch him due to the mysterious invisible barrier that suddenly formed.

Saber used her Mana Burst to improve her already impressive speed and aimed to slash at the Overlord with her concealed sword, but it was futile since Ainz has just activated [Greater Teleportation] before the attack connected, suddenly moving far away from his last position.

She wanted to protect Iri from Ainz, even though he was not the one who hurt her.

"Stay away, Caster! What are you doing?! We have an alliance, remember?!" The petite knight pointed her holy sword at him.

"It wasn't me, Saber. He's the culprit," he pointed to Kirei who was still fighting his familiar. Jack had already overwhelmed him by sheer speed and he couldn't keep up any longer. He thought of retreating, but he could still trade blows with her albeit it was a difficult task since she moved around the battlefield fast.

He made a gamble and threw one of his Black Keys at Ainz with all of his might so its speed could distract the girl and hopefully, injure Caster even if it were unlikely. Jack fell for the bait, afraid the attack would harm her father so she went to intercept it. But she was a bit too late as the knife was merely 15 centimeters from her father. But to her surprise, before the weapon could even hit, an invisible barrier bounced it back towards the fake priest with ease.

Jack was dumbfounded, but in hindsight it was expected since she believed her father was strong, enough to even bypass a Ruler's authority who banished her from the grail. She began to focus on him again but alas, he was already gone. He used that attack as a means of escape.

Upset since she didn't want to disappoint her father she started in pursuit of him but was stopped by Ainz himself.

"That's enough, Jane. Come back here." The elder lich commanded, making her reluctant as she tried to rebut.

"But, papa! We can still catch him. Please, let us pursue him!" She desperately begged for permission but was denied. Saddened by his disapproval she accepted it nonetheless.

-II—II-

'It's bad, really bad. I don't know why but that person gave me a bad vibe. We neatly blended with nature and yet, he seemingly found us like we were not even hiding. Who is he? How can he find us so easily?!' thought one of the alter-egos of the 19th generation of Hassan I Sabbah.

All of the Assassin's alter-egos had camouflaged themselves with the trees, grass and shadows. And with A+ Presence Concealment that they had they shouldn't be revealed unless they decided to attack. But this skull sword man managed to find and kill them one by one with ease.

'No matter what, we must retreat. This guy is dangerous. Far more dangerous than we had anticipated...' The alter-ego tried to communicate with the others after retrieving their master, but the alter ego didn't realize Hassan was already behind him.

The servant managed to notice his presence when had attacked. It was too late, his head had been sent flying after being completely cut off from his main body.

And thus, another one of the henchmen had been killed. King Hassan had already slain ten of them with no effort. The original Hassan I Sabbah, seeing this, spoke around one of the freshly killed bodies.

"Resist with all your bravery and might, your heads shall remain witnesses to my blade. Your faith might be one of the greatest, yet ye know nothing of the true meaning of the word. Fools, such limited knowledge can only carry you so far, none can ever hope to escape my sword." He declared, watching as the corpse dematerialized into particles of mana that were carried away in the air.

With his job done, King Hassan vanished returned to his contractor's side. He intentionally left the rest of them to escape so they could warn their comrades of who they had confronted just now, the Abyss of all Assassins.

END

TRIVIA CORNER

King Hassan in this story is exclusive only to the True King route. If you picked Fate-in time or Heaven Slayer, there is another exclusive character.

The mysterious woman is not OC. Speculate all you want.

AN: Well I guess that's it. I don't know if I can update faster, so see you again.