Shamna reigns as the queen and holy priestess of the desert nation Zilkhstan, leading the Farlaf Order. She shares a close but complex relationship with her younger brother, Shalio, whom she protects fiercely while strategically leveraging him as a vessel to deliver her "prophecies" to the populace, cementing her authority. Her driving motivation is the salvation of Zilkhstan after its economy collapsed in the wake of the Zero Requiem and the ensuing global peace, which destroyed demand for the nation's primary exports: mercenary soldiers and weaponry. To rescue her homeland, she orchestrates the capture of Nunnally vi Britannia, intending to exploit Nunnally's connection to C's World (the Collective Unconscious) to rewrite reality and establish Zilkhstan's dominance.

Physically, Shamna is a tall woman with long blonde hair, blue eyes, and a curvy figure. A distinct Geass sigil marks her pelvis. After becoming a "Failed One"—a unique condition granting eternal youth without full immortality or immunity to Geass—a Code mark appears on her lower abdomen. This halted aging, shared only with Lelouch, does not nullify others' Geass abilities.

Her Geass ability activates upon death, sending her consciousness six hours into the past. This grants her precognitive visions of future events, allowing her to strategically adjust actions to avoid fatal outcomes. Originally permitting standard future sight, her Geass evolved alongside her ideological shift toward utilizing death tactically. The ability manifests with a golden-yellow glow in her Geass sigil.

Personality-wise, Shamna projects self-centeredness and indifference toward subordinates, showing scant regard for their lives, possibly due to her Geass altering her perception of mortality. Despite this, her devotion to Zilkhstan and Shalio remains absolute. She views Lelouch as a foil, noting their shared traits: both leverage Geass for transformative goals, prioritize their siblings' well-being, and demonstrate strategic brilliance. However, she rejects his acceptance of historical progress, seeking instead to reverse time and restore Zilkhstan's former power.

During the events of *Re;surrection*, Shamna's forces ambush and capture Nunnally and Suzaku Kururugi. She reveals her plan to harness Nunnally's psychic resonance with Charles zi Britannia (her "wavelengths") to access C's World, compensating for her single Code. After Lelouch infiltrates her temple and kills her, her Geass triggers, enabling her to retroactively counter his tactics. Lelouch deduces her ability's mechanics and uses C.C.'s Geass immunity to bypass her foresight, ultimately commanding her into eternal sleep with his own Geass. Her defeat coincides with Shalio's death, permanently ending her influence.