Unidentified Sentinel variant

This Unidentified Sentinel Variant was an extremely large Sentinel-like machine used by the Forerunners during the Forerunner-Flood War. It is the largest Sentinel variant observed to date, dwarfing the Strato-Sentinel in comparison. Its armament includes an extremely powerful energy weapon, capable of firing a lightning-fast energy beam at long range and producing an explosion powerful enough to level entire cities. It is likely this machine was used to deal with massive flood infestations spanning entire population centers.

Trivia

 * The machine is only seen in the Halo Legends episode Origins.
 * Forerunner Tank, a level cut from Halo 2, featured the titular "Forerunner Tank", a massive Forerunner machine. It is possible that this Sentinel variant's design was derived or influenced by the unused concepts for the Forerunner Tank. It may even go as far as the Sentinel variant actually being the Forerunner Tank.
 * It is possible that the energy weapon used by the Sentinel variant may actually be a particle beam weapon, due to its extreme power. Its sheer destructive power dwarfs that of the Onyx Sentinel, the Monitor energy weapon, as well as that of the Spartan Laser.