The Bloody Valkyrie

The Bloody Valkyrie (鮮血の戦乙女) is a re-enactment game event in Mass for the Dead that was released on June 21, 2019 to July 1, 2019.

Background
This is a story you should have seen somewhere--. In order to deal with Shalltear who suddenly rebelled during the mission, he bets on the qualities and dignity of Ainz Ooal Gown as the lord, and challenges a battle alone in the overwhelming disadvantage.

Summary
With her Vampire Brides, Shalltear Bloodfallen, was given on a mission by Ainz Ooal Gown to capture humans for information on the New World. After saying goobye to Sebas Tian and Solution Epsilon who were on their own assignment, the vampires headed into the depths of a forest seeking the base of the bandits they just wiped out. The Floor Guardian hopes to please her master, in seeking out Martial Art users and humans that would not be missed like criminals. Seeing the bandits to fit at least one of the criteria, she and her minions soon find the cave where they are based in. Shalltear and her vampires begin slaughtering the bandits. The vampires are soon approached by one of the bandits named Brain Unglaus. Noting their odd appearance and the Blood Pool hanging in the air, he surmises that they must be magic casters. Shalltear clarifies that she is a divine magic caster. Brain states he's ready to fight, amusing Shalltear who believes he is overselling himself. The Floor Guardian orders one of the Vampire Brides to attack, but Brain counters with a forceful swing, slashing the Vampire Bride across the chest. Seeing that the woman though injured remained standing, Brain realizes that they are not normal foes and after witnessing the Vampire Bride heals herself, and Brain understands that he is facing a vampire. The Vampire Bride attempts to use mental abilities to manipulate him, but Brain reveals he possesses a strong will to resist such mind control. Brain slowly advances upon the vampire, who now seeing the difference in power starts to retreat. Shalltear takes the moment to tag in for her subordinate and faces Brain herself making it clear she is the master of the vampire and gives the warrior an introduction as a courtesy.

Brain thinks her challenge as nothing, but as he prepares to attacks her. Preparing himself he launches his original martial art [Field] allowing to expand his perception to a three meter radius. Combined with that he uses a second Martial Art: [IGod Flash], a high speed strike that he deemed to be in the realm of the gods. Shalltear bored at his preparation easily catching the strike using her fingertips. The vampire asks the Brain if he is done yet, drawing the ire from the mercenary. He tries again this time aiming low at her ankle, but Shalltear simply trod on the blade with her shoe. Brain panics at seeing all his perfected moves being countered by the vampire. To add further insult, Shalltear slyly mocks him, questioning his ability to perform Martial Arts. Angry he takes his blade to strike her once again, but Shalltear with a flick of her nail parries the blow. The mercenary continues his barrage of attacks and each one is deflected by the girl. In despair that all his training he put so much effort amounts to nothing before this vampire. However, he mentally breaks when Shalltear mentions that she never trained and was created as strong. His confidence shattered Brain breaks down in tears, much to the amusement of Shalltear. Turning his back towards her the warrior flees. Amused by his actions Shalltear then follows slowly behind to catch her prey. Transforming into her True Vampire she follows him outside the cave she runs into a group of adventurers. Regardless of who they are Shalltear decides to slay them all to sate her bloodlust.

Shalltear slays all save a woman named Brita, who is saved from certain death by her use of a potion. After being harmed by said potion, it snaps the vampire out of her blood craze. Shocked that it was a YGGDRASIL potion Shalltear has her Vampire Brides capture her. She then uses mind control on Brita to find out where she obtained such a potion. After being told that a man in black armor gave it to her in E-Rantel. Shalltear realized that man Brita referred to was her master Ainz Ooal Gown. Confused as to why Ainz would give a human this potion, she wondered if Brita was under orders from her master. Shalltear mistakenly believed that Brita is a part of Ainz's plans and she may have interfered.

Further questioning the adventurer, she learned that her team were part of E-Rantel's city's patrol searching for bandits in the area. Learning that Brita's team had one more member, a ranger, Shalltear realized that she made a grave mistake in allowing one to escape. Angry at herself for this slip-up she summoned ten Vampire Wolves to hunt down and kill anyone in the forest. After being given the order the summons surged into the woods as one. She decides to spare the woman as it may be part of Ainz’s plan and orders her forces to prepare to retreat. However the Shalltear psychically feels that all of her summons were immediately killed. This prompts her to investigate the cause, ordering her vampires to regroup with her after they tossed Brita with the other captives they found with the bandits. Turning into a True Vampire once again Shalltear rushes into the forest intent on destroying whoever attacked her summons.

In the Lemegeton, Ainz is greeted by Albedo who reports to him that Shalltear has rebelled. According to the last group that was with her she was tracking down a bandit base. It is strange that she has rebelled as just moments before she separated from her comrades they were talking about their loyalties to their creators. As for the two Vampire Brides that were with her, they have been killed. Ainz decides that they need to go into the Throne Room to confirm Shalltear's status. There by using the dungeon's administration system the two determine that Shalltear is indeed under the control of an outside influence. To gather more information, Ainz uses scrying magic to view Shalltear Bloodfallen who is maintaining her position. Since she has been mind controlled, before it was completed, Ainz states that he will have to use a Divine Item to free her which annoys him. A [Message] comes through from Narberal Gamma that the Adventurer's Guild in E-Rantel is looking for him. He tries to tell to stall for him, until she mentions it concerns a vampire. The situation having grown more complicated, Ainz tells Albedo to station summons around Shalltear to monitor her while he goes to deal with the guild until he makes a decision on what to do.

Back at E-Rantel, Ainz now donning his Momon disguise attends a meeting headed by the Guildmaster, Pluton Ainzach. There at the meeting, Pluton introduces Momong to Igvarge of Kralgra a mithril rank adventurer team. Before the meeting starts, Igvarge asks for what deed was Momon included in this meeting. Pluton then explains that Momon is a warrior who tamed the Wise King of the Forest and defeated two Skeletal Dragon s in the E-Rantel's Cemetery. Furthermore he is a warrior that is comparable to adamantite rank which shocks the mithril warrior. The guildmaster then goes on to the focus of the meeting, the vampire that was encountered by an adventurer team two days ago. The vampire had already killed five of them, and one of the surviving adventurers gave them a vivid description on its appearance and abilities such as its ability to create undead. From what Pluton learned from the Magician's Guild it would mean that the vampire is a powerful magic caster. Momon listening to this confirms that the vampire they are talking about is indeed Shalltear. Before they take any aggressive action on the vampire Pluton decides the adventurers should do some reconnaissance first. Momon immediately volunteers for the assignment claiming that he knows who this vampire is as he wishes to minimize the damage caused by Shalltear's appearance. So he concocts a story that the vampire is named Honyopenyoko, and that he has been hunting it. In addition, he shows that he possesses a Sealing Crystal containing a seventh tier level spell which he intends to use. Momon insists that Darkness will fight against Honyopenyoko alone, arguing that involving others in the fight will simply increase the number of casualties. Nearly all in the room acquiesce to his terms save Igvarge of Kralgra, who demands his group accompany Momon in the fight against the vampire, which the latter accepts. When they travel together to where the vampire is Kralgra and Darkness meet Albedo much to Igvarge confusion, until Momon states that he and his team will die here.

The witnesses having been taken care of, Ainz introduces Hamsuke to Albedo and orders Narberal to escort the hamster to Nazarick so it may be acclimated with the members of the tomb. Albedo and Ainz then head towards Shalltear and confirms that she is not only on standby, possibly due to an incomplete mind control magic, but wielding Spuit Lance. Despite having countermeasures against mind-control, the vampire has fallen under an influence of at least as strong as a Divine Item. To undo the spell on Shalltear, Ainz reveals his wish-granting magic ring, Shooting Star. To his shock, the magic fails. Ainz frantically orders a retreat, teleporting himself and Albedo to a safer location. Before Albedo asks what is wrong, however, Ainz goes through a tantrum of rage kicking the dirt in anger. His undead racial effect kicks in, and the Overlord calms down. Ainz tells Albedo the magic of a Divine Item didn't have any effect on the mind control placed on Shalltear which could only mean one thing that Shalltear was affected by a level greater than it: World Items. He didn't anticipate any World Items to exist in the New World and with their existence, Ainz first orders Albedo to recall all Floor Guardians outside of Nazarick to verify if they are comprised and to escort him to the Treasury.

At the entrance to the Treasury, Albedo and Ainz are joined by Yuri Alpha and CZ2128 Delta. Before the entrance, Ainz opens it using the universal password. The group enters a lobby area where they what appears to be Tabula Smaragdina, Albedo's creator. However, upon further scrutiny she quickly sees it as an impostor, causing Yuri and Shizu to prepare for battle. Ainz orders them to stand down and reveals that the impostor is really a Doppelgänger named Pandora's Actor, the Area Guardian of the Treasury. The Area Guardian resuming his natural form dramatically introduces himself and offers his services. Seeing that his master has come to the Treasury, the Area Guardian deduces that he has come for the World Items and that there is a situation that may threaten Nazarick. While painfully listening to his creation's antics, Ainz pulls Pandora's Actor aside and tries to impress him to act seriously which the NPC reluctantly agrees to try. After that, Ainz orders Albedo to give her Ring of Ainz Ooal Gown to Pandora's Actor so as to avoid being attacked by the security measures and follow him to the Mausoleum.

Inside the Mausoleum, Ainz shows Albedo the Avatara, golem statues made into the likeness of each of the Supreme Beings. Ainz created it as a memorial to his comrades and to safely store away their gear. He tells Albedo once day a statue of him will be here. Albedo takes it that Ainz means to leave them and begs him to stay with Nazarick forever. Ainz cannot promise her that and tells her that should he be gone, leadership of Nazarick and the other Floor Guardians wll fall to her. He tells her his intent to face Shalltear alone, despite her protests, stating it is his responsibility and he does not wish for his children to kill one another. Albedo seeing his determination, demands that he promise her one thing, to come back.

At Shalltear's location, Ainz Ooal Gown commands Aura Bella Fiora and Mare Bello Fiore to separate from him. Since they are now equipped with the World Items, he orders them to scout the area for any interlopers. Demiurge having returned to the Great Tomb of Nazarick, where he meets with Cocytus and Albedo. He asks what is going and learns that Ainz intends to face Shalltear Bloodfallen alone. Despite Albedo's confidence that Ainz will be victorious, Demiurge is afraid of the possibility that his master may be killed. He criticizes Albedo's acceptance of Ainz's decision, noting how she was most critical when their master went to E-Rantel to become an adventurer. Demiurge attempts to leave to assist his master but is stopped by Cocytus who was given orders from Ainz to prevent any interference. Demiurge relents, however, should Ainz fall he demands that Albedo step down as Overseer Guardian to which Albedo accepts, continuing to believe Ainz will return. Ainz approaches where Shalltear is still in her standby mode. Seeing it as a good time as any, Ainz prepares for battle, buffing his stats with magic enhancing spells and arms himself with Quick-Change Items. Lastly, he prepares to cast the Super Tier Magic: Fallen Down. When the spell is completed, it causes massive damage, resulting in the magic burning down the area.

Where the Floor Guardian stood calmly in a stationary position she now appears to be not only armed with Spuit Lance but also donning her Valkyrie Armor. Despite looking relatively unharmed, Shalltear laughs and admits that the attack did some damage to her and she prepares to attack her master. The two exchange barbs and attacks at each other. Shalltear gains the upper hand, but Ainz manages to counter her using his experience and deception. Shalltear then summons her Einherjar, a physical double. Ainz manages to counter the two attacks and defeat the double, though he sustains attacks from Shalltear, with Spuit Lance draining his mana. Eventually, Ainz uses Widen Magic: Cry of the Banshee. The area turns bright and as the light fades, the surrounding area having turned into sand. The attack leaves Shalltear unscathed. Ainz now low on mana, Shalltear prepares to finish him off. She asks if he has any last words. Rather than admit defeat Ainz declares that she was sloppy and that everything is going according to his plan. Shalltear believes Ainz is bluffing but is now wondering what Ainz has yet to retreat. Scared at the possibility that she walked into a trap she retaliates, intending to pierce Ainz with Spuit Lance. Ainz is suddenly garbed in silver armor. The Floor Guardians watching from Nazarick realize that the armor is Touch Me's personal armor.

Shalltear cries in pain as she is slashed across the chest. She sees that her opponent now wields a katana, which she recognizes as Takemikazuchi MK 8, another weapon of the Supreme Beings. Ainz declares that he possesses the strength of all Forty-One Supreme Beings. Ainz follows up with another attack but is blocked by Shalltear. He dismisses his weapon making the vampire believe Ainz is wide open. However, her attack is rebuffed by the appearance of two daggers, Amaterasu & Tsukuyomi. Ainz continues his attacks using one Divine Weapon after another. Demiurge deduces that Ainz used [Perfect Warrior] to wear the armor without penalty. Frustrated, Shalltear manages to pierce Ainz with her Spuit Lance and declares that her weapon will drain Ainz's HP. However, as she pulls back, she hears a familiar voice from Ainz's watch. The latter declares that battle to be over. Shalltear angry at Ainz's overconfidence launches an onslaught of attacks.

Ainz begins activating his Super-Tier Magic with Shalltear in the center. Just as he is about to activate a Cash Item to quicken the spell Shalltear rushes forward and nearly lands a killing blow on Ainz. However, she is suddenly distracted by a skill. Before she could determine who activated the skill Ainz completes his spell and Shalltear is engulfed in oblivion. Before she fades Shalltear admits to her master as the victor.

Elsewhere Mare Bello Fiore asks his sister, Aura Bella Fiora of Shalltear's defeat. Ainz returns to Nazarick where he is about to prepare to resurrect the Fallen Floor Guardian. The remaining Floor Guardians wary that Shalltear may still be under the influence of the mind control even after her resurrection prepare to subdue her. Shalltear is successfully brought back to life, however, she is unable to recall any memories of the last five days.

Shalltear realizes that her breast pads are missing and her reaction irritates her colleagues on her priorities. As Ainz watches his 'children' he feels the nostalgia of the time with his comrades. Rather than punish her, Ainz takes responsibility for the events that transpired, experiencing a moment of unbridled laught to his NPCs confusion.

Trivia

 * The scenarios in this game event covers the events from Overlord Volume 03.