- "We act as one, and united we cannot fall."
- — Attributed to Commander Shadowsun
Shas'O Shaserra, better known as Commander Shadowsun to the military forces of the Imperium of Man, and also called the "Spearhead of the Greater Good", the "True Disciple of Commander Puretide" and "Heroine of the Third Sphere Expansion", was the commander of the T'au Fire Caste's military campaign that carried out the T'au Empire's Third Sphere Expansion. After the alleged betrayal of Commander Farsight (known as Shas'O Shovah or simply O'Shovah in the Tau Lexicon), the T'au Empire's ruling Ethereal Supreme Aun'Va selected a more-steadfast replacement to conduct the Third Sphere Expansion of the T'au Empire. The great Ethereal selected Commander O'Shaserra for this important role.
O'Shaserra is a dynamic leader who rose to recent fame in the battles of the K'resh Expansion. There, she smashed the Ork menace, and her cadres suffered historically low casualties in return. All of Shadowsun's victories are marked by unrivalled efficiency, a trait not surprising from one of Commander Puretide's most promising pupils. Over 300 Terran years ago, O'Shaserra was a brilliant young warrior; her successes and matchless performances at the Fire Caste academies earned her recognition as one of the most able military minds in the T'au Empire. As such, she was granted the honour of studying personally under the ailing but legendary Commander Puretide. Despite being the youngest of all Puretide's proteges, O'Shaserra scored exceptionally well in all simulations, outstripping all others, save one -- the most highly favoured of all Puretide's students, Commander O'Shovah (Farsight). From the start, theirs was a bitter rivalry, as the two most gifted Tau Commanders in the Empire strove to gain their wizened master's approval.
During the battle on the Dal'yth Sept world, where the Imperium's Damocles Gulf Crusade was finally halted, it was Commander Farsight's audacious counterattacks that drew the most attention; however, they would never have been possible without O'Shaserra's patient ploy to draw out and overextend the Imperial battle lines. This ongoing competition between the two Commanders was abruptly halted by the death of the venerable Commander Puretide. The Ethereal Council was not fully convinced the mindcapture devices and holograms of the Earth Caste engineers would be able to recreate the teachings of their fabled mentor. So, to ensure Puretide's teachings were preserved for future generations, it was decided that several of his top students would be placed in stasis. Upon the orders of the Ethereal Council, a select few, including O'Shaserra, slept in frozen animation, unaging, until a time came when they would be most needed; a time of great expansion and furious battle.
Although Aun'Va had planned to awaken Commander O'Shaserra at the dawn of the Third Sphere Expansion, the largest Ork invasion of the T'au Empire accelerated the Ethereal Supreme's meticulous calculations. Yet even this the sagacious Aun'Va turned into an advantage. Appearing in a time of great need, O'Shaserra has once more proven herself a patient huntress, meticulous in her planning, yet swift in action. Her ability to draw foes into well-conceived killing zones lured numerous Ork armies to merciless deaths during the fighting of what is now called the Great War of Confederation. Yet, as the situation dictated, O'Shaserra could be bold. In order to end the fierce fighting in the K'resh Expansion, she led a Stealth Cadre straight into the heart of the Ork encampment to deliver a killing stroke. Timing her strike to coincide with an artificial eclipse, the T'au forces used the Jetpacks of their XV25 Stealthsuits to deploy from low-swooping Orca dropships.
Under the cover of the unnatural darkness, the Greenskins never knew what hit them. In an instant, their leaders were riddled by Burst Cannons before being finished off with searing shots from Fusion Blasters. It was O'Shaserra herself who personally sought out and targeted the Warlord bringing down the hulking alien with precision fire. As the alien hordes milled in confusion, the rest of O'Shaserra's cadres joined the fray. Without their bosses to lead them, most of the Orks panicked and fled, only to run into well-placed ambushes. By the time the sunlight burnt through the obscuring veil, the battle was over and a new Fire Caste legend was born.
Aun'Va was quick to promote the dedicated Commander, for in her he saw embodied all that was noble about the Fire Caste's pursuit of the Greater Good. Here was a Tau Commander who would not shirk from duty, who would not forget her vows to her people or her loyalty to Aun'Va himself. When he declared the Third Sphere Expansion, Aun'Va also announced the warrior who would spearhead the most important of its attacks -- Commander O'Shaserra, now called Shadowsun in honour of (what was then) her greatest triumph.
In her first speech as Supreme Commander, O'Shaserra made her address from the Mont'yr battle dome, the site where Farsight had famously trained. Arriving resplendent in her new prototype XV22 Stealthsuit, it was a sight to stir the martial hearts of all who viewed her. With the entire Fire Caste watching, Shadowsun began by firing her weapons at the statue of Farsight, obliterating it in a burst of white-hot desecration. As the dust settled, she outlined the new campaigns they would soon embark on. She spoke of honour, the sacred Code of Fire and the all-important law of the Tau'va. After this address, every Fire Warrior shouted in one voice, ready to follow their new Commander to any end.
Within Terran days, the Third Sphere Expansion had begun, and under Shadowsun's leadership, the T'au Empire has proven unstoppable. With Imperial attention elsewhere, and the Tyranid and Ork menace temporarily contained, Fire Caste spearheads drove into the outlying systems of the Damocles Gulf, the Perdus Rift and even beyond, forming five new T'au colonies in a halo around the original Sept worlds. Leading from the front, Shadowsun seems to be everywhere at once and her assault on Agrellan, a Hive World of the Imperium, during what became known as the Battle of Mu'gulath Bay, has opened up the entire Dovar System.
However it was at Mu'gulath Bay that Shadowsun encountered Kor'sarro Khan of the White Scars Space Marines, who inflicted horrendous casualties upon her command staff and drove the normally calm Tau Commander into a fury. In her rage and overconfidence, Shadowsun led an offensive that resulted in a stinging T'au defeat. Having barely escaped the Imperial ambush with her life, thanks only to the brave sacrifice of her personal retinue, Shadowsun swore to redouble her efforts in the campaigns of the Third Sphere Expansion.
Though successful during the Prefectia Campaign which followed the first battle on Mu'gulath Bay, Shadowsun was surprised when the Imperium used the war as a distraction to strike at Mu'gulath Bay, the former Imperial world of Agrellan, once more. During this bloody Second Agrellan Campaign, Shadowsun led an effective T'au resistance but could not stop the destruction of Mu'gulath Bay or the death of the Ethereal Supreme Aun'va at the hands of the agents of the Officio Assassinorum. Shadowsun herself only survived the destruction of Mu'gulath Bay due to her earlier wounding at the hands of a Callidus Assassin, which forced her to recover aboard a T'au starship. Free from the restraints placed on her by Aun'va and grateful to O'Shovah for his aid during the battle, Shadowsun secretly leaked information to her former ally that the Ethereal Council had ordered her to capture him.
- XV22 Stealthsuit - This experimental battlesuit, gifted to O'Shaserra, incorporates the latest advances in cloaking technology, targeting systems and miniature shield generators.
- Pair of Fusion Blasters - Fusion Blasters are anti-tank weapons that reduce reinforced armour to molten slag in the blink of eye.
- Advanced Targeting System - This specialised target acquisition system enables the battlesuit to identify and pick out priority targets in the midst of battle.
- MV52 Shield Drone - Commander Shadowsun is often accompanied into battle by prototype drones.
- Codex: Tau Empire (7th Edition), pg. 38, "Commander Shadowsun"
- Codex: Tau Empire (6th Edition), pp. 58-59
- War Zone Damocles: Kauyon (7th Edition), pp. 6-7
- War Zone Damocles: Mont'ka (7th Edition), pp. 105-110