Threnody

Threnody (also known as Shield 0927) is a Forerunner Shield Installation in the Gamma Serpentis system. It was originally intended to protect sentient lifeforms from the effects of the Halo Array and the Flood however it was never completed by the Forerunners and remains a dormant shell monitored by 823543 Adjudicator Sentry and a handful of sentinels.
==Background==
Threnody's surface is engraved with blue-glowing symbols and patterns of Forerunner origin. The meaning of many of these symbols remain unknown to even the top researchers of ONI or the UNSC.
A Forerunner Warrior-Servant, Rays of Dying Stars during the final Forerunner-Flood war fled to the abandoned shield world aboard a Picket cruiser after his fleet was destroyed at the hands of the Flood. From here, he, lived alongside the local sentinels and his handful of crew. His current status is unknown despite thorough research on the terminals on the planet which mention Rays of Dying Stars heavily.
In reality he is alive, sealed within a stasis pod along with his crew in the picket cruiser he arrived in. As the master of 823543 Adjudicator Sentry, he ordered that a structure be built as to lock the cruiser into the surface of the installation to prevent his capture by the flood.
==First Battle of Threnody==
On March 28 2555 the Halcyon-class light cruiser UNSC Last unto Dusk began investigating the shield world. The vessel was pulled in by the shield world and subsequently crashed into the surface of Threnody, barely missing a collision with a Library. 
Several platoons of marines travelled to the interior of the Library where they met 823543 Adjudicator Sentry and the sentinel forces present. The monitor showed the marines the location of a gravity well which could allow the cruiser to escape the planet if deactivated.
However as the teams began to set out to deactivate the gravity well, a pursuing Vestige Covenant fleet of CCS-class battlecruisers and CRS-class cruisers exited slipspace near the planet but these too were sucked into the world, heavily damaging or destroying many of the ships but still leaving a handful of larger ships intact.
They preceded to assault the UNSC forces at the gravity well complicating an originally easy operation. The battle came to a close as SPARTAN-III Gregory-A218 hijacked the CCS-class battlecruiser Valorous Spoils, crashing it into the gravity well. The UNSC Last unto Dusk quickly left the planet for UNSC space to report their discovery of Threnody.
==List of Appearances==
*Halo: Probrum