A planet, and a former batarian holding.
Even before the Reaper War, few colony worlds - batarian or otherwise - had as tumultuous a history as Xamdos and its notorious tyrant, Arkoztemates. One of the so-called ‘breadbaskets of the Hegemony’, Xamdos began as a dead world within the narrow habitable zone of a red giant, and proved to be one of the most successful examples of planetary terraforming in galactic history. Originally undertaken by a cooperative of Khar'shan-based merchant families, it seemed the batarians could do no wrong in their efforts on Xamdos. From redirecting comets to establish a freshwater atmosphere to developing an ecosystem friendly to organic life, every effort taken by the cooperative was a success, and after only a century and a half of carefully-planned terraforming the vast, grassy prairies of Xamdos were already exporting food. The success of Xamdos was, at least in part, the motivation behind the batarian colonial efforts on other barely-hospitable worlds like Pragia, though few proved as remarkable.
As the Hegemony became more autocratic, Xamdos was fully incorporated into the colonial system, becoming a tributary of Khar’shan - with a governor and military garrison - rather than a semi-independent trading partner. The founding families’ fortunes waned on Khar’shan under the new regime, but they remained by far the most powerful forces on Xamdos itself, operating much like the Camalan Grusto do today. Always a superstitious government, the Hegemony invested heavily in Xamdos, seeing the world as a sign of good fortune. Numerous batarian agencies established research and development facilities there, including Batarian State Arms and the more secretive branches of the government such as StateInt, StateSec, and the Special Interventions Unit. Over the course of a century of rule from Khar’shan, Xamdos turned from productive agricolony into a thriving scientific hotspot, one of the deliberately worst-kept secrets in the Hegemony, who quietly propagandized the world as an example of batarian ingenuity and power.
As the significance of Xamdos in both economic and military spheres increased, the position of governor became hotly contested, with the wealthiest and most prominent families from Khar’shan vying to have the post occupied by one of their own. The end result was a series of nearly a dozen governors of little talent and no qualification beyond money and connections, and the Xamdosian agricultural output plummeted despite the efforts of the founding families to mitigate the damage of poor rulership. Large-scale building projects took precedence over irrigation system maintenance, and taxes were repeatedly raised to fund grand displays of opulence, concealing the fact that the colony was horrifically mismanaged. Eventually a near-bloodless rebellion took place, the founding families of Xamdos funding teams of mercenaries and placing substantial bribes to overthrow the governor and his immediate supporters. In his place they installed the mastermind of their plan, Arkoztemates.
The Hegemony’s response was swift but subdued, as they were reluctant to tarnish Xamdos’ carefully-constructed image as a batarian paradise of innovation and productivity. A small team of SIU commandos with StateSec and StateInt support was inserted into the capital with the intention of publicly assassinating Arkoztemates, but were never heard from again. Their fate only became clear when Arkoztemates returned their heads to the Hegemony, along with double the prior yearly tribute, a clear statement of both the colony’s continued loyalty to Khar’shan and their intention to remain self-governing. Rather than crush the revolt, the Hegemony quietly recognized the legitimacy of the new government, which took a form similar to a Republic governed by Arkoztemates, with a council of advisors formed from the founding families. The reign of the tyrant had begun.
It remains a matter of some scholarly debate why the Hegemony acted so irregularly regarding the Xamdosian revolt, but it’s generally agreed upon that their actions were informed by a healthy knowledge of exactly what kind of prototype weapons were in the hands of the rebels following their victory. This view, formed with the benefit of hindsight, tends to overlook that in addition to doubling the yearly tribute, Arkoztemates welcomed the continued scientific research and development that had made Xamdos such a success, thereby winning the favour of several military factions clandestine and otherwise.
Regardless, the installation of Arkoztemates didn’t result in the change the families had hoped for, and in fact the new tyrant magnified almost every complaint that had motivated the revolt. Massive building projects were expanded even further, taxes increased, and rumors of debauchery and even blood sacrifice in the palace only gained strength as the influence of a local cult grew. The tyrant brought in mercenary bodyguards, who combined with a complete lack of restraint managed to foil multiple assassination plots and quell potential uprisings before they happened, using his own extensive experience in planning such revolts to prevent others from succeeding as he had. Even the tyrant’s name dates from this period, as he had prior records expunged and destroyed upon his accession. The tyrant’s reign culminated with a purge of the founding families amidst rumors of insanity only a few months before the Reaper War.
The Reaper War
The final battle of Xamdos is unique even among the extraordinary events of that conflict. Despite the complete lack of witnesses, a network of old Hegemony weather satellites recorded the entire sequence of events and once the relays re-opened it took little enough time for these recordings to reach the extranet. The first Reaper vessel to enter the system, a dreadnaught presumably expecting the same light resistance the Reapers faced across the rest of the Hegemony, was met with a planetary weapon of tremendous magnitude that utterly destroyed it. Satellites recorded a shockwave that levelled an entire city at the moment of firing, rendering the weapon useless when further Reaper ships arrived. Various other planet-based weapons and orbital defense platforms using prototype weaponry proved unable to stop the Reaper advance. As Reaper forces entered the atmosphere a black cloud of indeterminate origin began to spread from several points on the planet surface simultaneously, soon completely engulfing the world and all the Reaper forces thereupon, which were never seen leaving. Remaining Reaper forces in the system withdrew, and subsequent expeditions to the planet have revealed that the entire atmosphere is corrosive to both organic and inorganic materials, returning Xamdos to the state in which the batarians found it, barring the massive stone cities constructed by the tyrant and his predecessors, which orbital surveys have revealed to be largely intact but entirely devoid of life.
The weapon unleashed on Xamdos was presumably not of Reaper origin, as it destroyed their forces along with all other life on the planet. No samples have been collected and no studies conducted, as the atmosphere remains entirely destructive to any and all who approach, and even the nature of the weapon, whether chemical, biological or technological, remains entirely enigmatic. Nevertheless, the satellite network around Xamdos still functions and signals the arrival of new vessels, scavengers and others foolish enough to attempt the surface. Rumors persist that the satellites occasionally signal departures, as well, but such reports are categorically denied by the Confederacy. Council and Confederate authorities have declared Xamdos a condemned world and placed it under official quarantine, albeit one which is enforced only by the lonely satellites still monitoring the planet’s weather patterns, such as they are.
According to Chak Zi'Kratarg, who claims insight into many things due to yahg analytical ability, famed "dark magician" Unfathomalice is likely a female batarian from Xamdos.