During a previous Phoenix cycle, the Mothman Eclipser witnessed the catastrophic destruction of its ancestral homeland when the great bird's rebirth triggered natural disasters that decimated the region. Its prophetic abilities later revealed visions of even greater calamity should the current Phoenix cycle complete, driving it to join Zephyr Shadowcloak's cause after the enigmatic leader promised a way to permanently break the cycle of destruction.

The Mothman Eclipser's massive wings can generate unnatural darkness, temporarily blocking the Phoenix's energies and creating localized 'eclipses' that weaken fire-based powers. Its glowing red eyes can perceive future disaster paths, allowing it to identify critical junctures where the Phoenix's rebirth cycle can be disrupted most effectively. Though powerful, it cannot maintain its eclipse effect indefinitely and must retreat to shadowy realms to recharge after extended use of its abilities. The creature possesses an innate sensitivity to Phoenix ash, enabling it to track the sacred substance across vast distances and identify Ashen Pilgrims by the residual energy they carry.

The Mothman Eclipser serves as both an elite scout and prophetic advisor to Zephyr Shadowcloak, using its disaster-sensing abilities to identify crucial moments in the Phoenix's rebirth cycle where intervention would be most effective. It leads specialized disruption teams that target sacred sites ahead of the Ashen Pilgrims' arrival, using its eclipse-generating wings to neutralize accumulated Phoenix energy and create obstacles that delay or prevent the completion of necessary rituals.