Apollonia Vaar, the Black Knight, acts as the Erste Empire's top adviser and de facto ruler. She forged Erste from a minor nation into a military superpower in a short time, though her personal motives seem distinct from the Empire's own objectives, suggesting independent goals beyond imperial authority or power.

She knows Lyria's abilities and often appears with a mysterious girl named Orchis. Her interactions with the Grandcypher crew involve presenting trials or challenges before vanishing, positioning her as an enigmatic figure testing their capabilities. Her strategies were instrumental in securing Erste's dominance across the Phantagrande Skydom's major islands.

In combat, she wields the sword Blutgang and wears specialized armor. Her techniques include **Obsidian Moonlight**, shattering space to unleash dark energy, and **Sword of Delusion**, summoning pillars of darkness that enhance her abilities. She employs elemental magic via **Quadspell**, simultaneously attacking with fire, water, earth, and wind while inflicting status ailments like Burn and Delay. Her **Onyx Drain** absorbs life force and strength from targets to heal herself and amplify her power; Blutgang passively activates this ability when she nears critical condition. **Acumen** induces fear to stall enemy actions.

Her resilience includes resistance to memory manipulation and causality alteration, a trait shared among Skydwellers who can defy the Otherworld's timeline revisions through willpower and strong bonds. She also withstands radiation effects from prolonged exposure to **Dark Essence**, a hazardous material she weaponizes to amplify attacks, though its overuse causes severe fatigue and weakness. After her defeat by the crew and acquisition of Blutgang, she ceases using Dark Essence due to its debilitating side effects.

As a Luminary Knight, she possesses capabilities comparable to entities like the Eternals, including power absorption from Primal Beasts. Blutgang's awakened state surpasses standard Luminary Knight levels, enhancing her attack potency and critical hit likelihood. Her combat effectiveness increases in critical states via **Sword of Despair**, which boosts her defenses and attack potency as allies diminish.

Her background remains partially undisclosed, with no confirmed age or personal history beyond her rapid rise in Erste's ranks without formal military training. She commands strategic brilliance in governance and combat, leveraging her understanding of magic, energy manipulation, and psychological tactics.