Duel at the Elven Royal Castle

Duel at the Elven Royal Castle was a battle between one of the Sorcerer Kingdom's 6th Floor Guardians, Mare Bello Fiore, and the Extra Seat of the Slane Theocracy's Black Scripture, Antilene Heran Fouche. It would end up being the spark that led to war between the two nations.

Background
Whilst on a covert mission in the Elf Country with the 6th Floor Guardians, Aura and Mare, to get it's Dark Elf population to migrate to the Sorcerer Kingdom, Sorcerer King Ainz learned that the Slane Theocracy would soon be attacking the Elven Capital. Not wanting the treasures within to just fall into enemy hands, he infiltrated the city alongside the twins with the intent to loot the treasury. However, this led them to cross paths with Elf King Decem, who assumed the Floor Guardians to be his grandchildren and ordered them to bear his offspring. This enraged the Sorcerer King and a battle ensued which ended in Ainz's victory. However, the Elf King managed to escape, prompting Ainz, who wanted his equipment, to send Mare after him while he and Aura looted the treasury.

Meanwhile, the Theocracy launched an assault on the Elven Capital, intending to finally end their long-term war with the Country. As part of this offensive, the Theocracy sent Antilene Heran Fouche to assassinate the Elf King. Intercepting him in his throne room as he attempted to flee the country following his loss to Ainz, the Elf King assumed her to be Aura and Mare's mother. However, Antilene had no idea what he was talking about and proceeded to kill the already exhausted monarch with ease.

However, after Antilene completed her mission, Mare entered the throne room. Assuming him to be one of the grandchildren who the Elf King mentioned earlier (and a girl due to his cross-dressing), she attempted to kill him by throwing the monarch's corpse at him. However, Mare dodged it, surprising her. Striking up a conversation, Antilene is shocked when Mare introduced himself as being from the Sorcerer Kingdom, recalling the "Thousand Leagues Astrologer's" report on the Dark Elf who accompanied the Sorcerer King during the Massacre at Katze Plains.

Antilene continued to question Mare, but all she got were some stuttering replies that did not reveal anything aside from him not being alone. Concluding that she will not get any anything from this conversation, she decided to just subdue and kidnap him so she might properly interrogate him later.

Battle
Closing the distance between them instantly, Antilene swings her scythe at Mare's legs. However, he blocked it with his staff. Although surprised at being countered so easily, Antilene continues swinging her scythe as a confused Mare repeatedly deflects her strikes whilst stumbling back to try to create some distance between them. Realizing her opponent's strength, Antilene concludes that she will have to settle this quickly and gives up on abducting Mare in favor of just killing him and taking his corpse to be [Resurrected] later.

Antilene's surprise attack failing meant that the fight would now become a battle of attrition. Having concluded Mare to be a fighting type, she is shocked when he buffs himself with [Power of Gaia] and [Elemental Form - Earth]. Having no idea what class those spells fall under, she uses the Inquisitor skills [Denounce Heretic] and [Sentence Heretic], which increases MP costs and spell failure rates for Priests that believe in a different god than her.

Taking the offensive for the first time in the battle, Mare rushes at his opponent at incredible speed and swings his staff at her. Despite being able to easily dodge the straightforward attack, Antilene chooses to block it with her scythe to feel the extent of the buffs. However, the strike is so strong that she is shoved to the ground and forced to use all her strength to push it away. With Mare right open now, Antilene swings her scythe at his belly with the Martial Arts [Greater Wind Stride], [Steeled Arm Strike], [Greater Piercing], [Greater Ability Boost], and [Greater Possibility Sense]. Before she can pierce his organs, Mare uses the skill [Instant Counter] to knock Antilene away.

Using the Martial Arts [Pain Suppression] and [Greater Wind Stride], Antilene regains her footing and applies first aid with the 3rd-tier spell [Heavy Recover]. Mare, meanwhile, uses a Scroll containing the 6th-tier spell [Heal] to completely heal his wound. Watching the little progress she achieved being undone, Antilene once again attacks with her scythe, this time aiming for his wrist. However, he tanks it with his right arm before swinging his staff at his opponent with her left. Unable to avoid the attack, Antilene uses the Martial Art [Greater Reinforce Defense] to endure the hit. Still, she could not completely negate the damage.

Putting some distance between them again, Antilene found that, as it stands, the battle would likely end in her opponent's victory. As she considers using the spells infused into her scythe, Mare questions why she is not attacking. Taunted, Antilene uses the Martial Arts [Double Air Slash], [Steeled Arm Strike], and [Flow Acceleration] to fire two blades of air at him. However, Mare once again just tanks the hits whilst closing the distance between them and swinging his staff at her, which Antilene barely avoids.

As Antilene retreats and Mare gives chase, she finally starts using her scythe's spells by summoning five Spartiates. With the Undead occupying her opponent, Antilene jumps behind him to pincer him, only for him to jump out of the encirclement. As Antilene orders the Spartiates to attack, Mare uses a scroll containing the spell [Firestorm] to severely burn both her and the undead. Undeterred, the Spartiates hit him with their spears, to no effect. Now knowing that only her attacks are effective, Antilene swings her scythe at her opponent's legs, slicing through one of her summons in the process. However, Mare is barely affected and, seeing an opening, swings his staff at her, though a Spartiate pushes her out of the way.

While Mare destroys the remaining Spartiates with a spell, Antilene regains her footing. Seeing that her opponent was only reacting to her attacks, Antilene feigns aiming for his wrist before redirecting her attack and slicing his unprotected neck. However, Mare then once again forces her back by hitting her with his staff. Repositioning herself again, Antilene sees that her attack once again failed to do major damage.

Sensing his opponent's discomposure, Mare suggests she surrender. While the proposal disgusts her, Antilene briefly considers it, needing a way out of the current situation. However, she concludes that her opponent must be attempting to buy time and attacks again. Aiming her scythe at Mare's face, he countered the attack for the first time since the start of the fight. He then follows with an attack of his own using his staff, but she barely dodges it using the [Greater Evasion] and [Instant Counter] skills. Nonetheless, Antilene learned from this exchange that she can get her opponent to counter her attacks only when aiming for the face.

As Mare and Antilene continued exchanging blows, the latter considers using her trump cards but wonders if now is the right time. However, after being blown away by one of Mare's staff strikes, she concludes that she cannot wait anymore and resolves to use her first trump to end the fight here: [The Goal Of All Life Is Death], which she can use by copying the God of Death, Surshana's, Eclipse class using through her scythe using her [Psychometry] Talent. Seeing his opponent use this skill, Mare expresses shock for the first time in the fight.

Antilene then uses her scythe's insta-death spell, [Death], to start the skill's 12-second countdown, after which it would activate with a 100% success rate. Acting quickly, Mare casts the self-resurrection magic [Phoenix Flame] before charging at his opponent and desperately trying to get a hit on her, which would cancel the skill. However, Antilene easily dodges his attacks. Upon the timer running out, though, [Death] has seemingly no effect due to the resurrection spell Mare cast earlier. Freezing up in shock at her trump card being blocked, Antilene is then once again hit and nearly falls to the ground.

Her trump card having failed, Antilene concludes that this battle is lost and begrudgingly decides to flee. To create an opening, she uses her second trump card: an Einherjar summoned using her Lesser Valkyrie class. Once again shocked, Mare responds by summoning an Earth Elemental before sacrificing it with a Elemental Gacha to summon a stronger Elemental. Mistaking the creature for Elf King Decem's signature summon, Antilene once again starts speculating about Mare's true identity. Connecting the dots, she comes to a terrifying conclusion: the Slane Theocracy accelerating its war with the Elf Country was all part of the Sorcerer King's plan to annex the nation by coming to the elves' aid and installing Mare as a puppet ruler.

Believing she had fallen into a trap, Antilene once again considers fleeing while Mare offers her another chance to surrender. However, she concludes that all she can do now is foil the Sorcerer King's plot or die trying and rushes toward her opponent while her Einherjar does the same with the Earth Elemental. However, the Elemental takes a defensive stance to protect its master, prompting them to attack it instead.

As Antilene and her Einherjar continue fighting the Earth Elemental, she notices Mare seemingly running away, causing her to conclude that he must be at his limit. However, he then turns around and uses his remaining MP to activate the trump card of his Disciple of Disaster class: [Petit-Catastrophe]; unleashing a current of energy surpassing even Super-Tier spells. While it instantly destroys the Earth Elemental and Einherjar, Antilene manages to resist the skill for a while through sheer willpower before ultimately losing consciousness.

Aftermath
Due to Antilene's ability to use both The Goal Of All Life Is Death and Einherjar, Mare believed that she might have observed his master's fight with Shalltear. He thus decided to prioritize her retrieval over that of Elf King Decem's corpse and carried her out of the throne room.

[Messaging] Ainz and Aura, the two swiftly arrived before Mare. Upon being informed of what happened, the Sorcerer King opened a [Gate] and had Entoma take the unconscious Antilene to Nazarick's Frozen Prison for interrogation. However, Mare warned the monarch that Neuronist Painkill will probably be unable to restrain her, prompting him to put Aura in charge of guarding the prisoner. The Sorcerer King and the twins then used the portal to leave the Elven Royal Castle, although Ainz was slightly disappointed that Mare had left behind the Elf King's corpse and equipment.

While the Elf King's death allowed the Slane Theocracy to conquer the Elven Capital, Antilene's capture would prove to be disastrous for them. Using [Control Amnesia], Ainz read her mind and discovered that the Black Scripture were behind Shalltear's brainwasheding. Enraged, the Sorcerer King summoned Albedo and ordered her to halt all their operations in preparation for a full-scale war against the Theocracy.