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The Mantis was one of the successes of Projects HRUNTING and YGGDRASIL.

Project YGGDRASIL was the umbrella name for initiatives carried out by the Materials Group, aimed at re-engineering the strategically significant technologies and components of the MJOLNIR Powered Assault Armor for mass production and systems integration into new and existing combat vehicles of the United Nations Space Command.[1]


Development history[edit]

The YGGDRASIL initiative was headed by Vice Admiral Danforth Whitcomb during the Human-Covenant War as a response to the exceedingly expensive cost of the MJOLNIR Powered Assault Armor systems in use by the SPARTAN-II program. YGGDRASIL was designed by Whitcomb and the Office of Naval Intelligence as an industry-led work group tasked with adapting MJOLNIR-derived technologies and the one-off results of Catherine Halsey's research for mass production and implementation within other projects.[1]

These efforts met with mixed success during the war due to a lack of engineers and high-tier manufacturing facilities.[2] A consolidation of projects was conducted by ONI in 2535, leading to YGGDRASIL being paired with much older Project: HRUNTING, which had reached a dead end in its own research into powered exoskeleton technologies. ONI and Materials Group funded a program which paired both project's scientists and engineers, with support from corporate partners such as Lethbridge, Beweglichkeitsrüstungsysteme and Hannibal Weapon Systems. The program, referred to as HRUNTING/YGGDRASIL, made surprisingly rapid progress though the program's inherent compromises and and aggressive cost accounting meant there were many false starts and nonviable prototypes. Nonetheless, a particular approach was identified as having promise; the Armor Defense System (ADS) combined proven exoskeleton design with cost-effective variants of MJOLNIR-derived technologies with at least three specific product lines identified as having a tangible strategic impact.[1]

Once the conflict ended, the full potential of YGGDRASIL was realized.[2] Project: YGGDRASIL remains an umbrella project for the "democratisation" of advanced military R&D - of which MJOLNIR is now only one element.[1]


Project: YGGDRASIL primarily focused on integrating the products of Catherine Halsey, and the MJOLNIR program as a whole, for application in other development projects across the UNSC. As such, little is known of the YGGDRASIL program's specific innovations - with most of their known products developed under the HRUNTING/YGGDRASIL Armor Defense System banner. The ADS systems incorporate cost-effective variants of MJOLNIR technology such as neural interfaces, portable fusion power plants, energy shielding control BIOS' with proven exoskeleton designs pioneered by the HRUNTING program.[1]

Mark I ADS[edit]


The Mark I ADS was one of the earliest refinements of the UNSC's combat exoskeleton designs, tracing its visual design back to the HRUNTING Mark I exoskeletons employed during the colonial era. The Mark I was crewed by one operator and armed with a huge array of heavy weapons. The prototype unit for the Mark I was undergoing testing at Weapons Research Facility T12A on Algolis when the Covenant invaded the planet in 2549. The unit was ultimately used by an unnamed Marine to fend off the Covenant while the staff escaped, though ultimately was destroyed when the suit's nuclear self-destruct was triggered. This event destroyed the Mark I and the facility which created it.[1][3][4][5]

Following the war's end, some of the Mark I ADS data was salvaged from the rubble on Algolis, leading to the creation of the Mark I [J] "Green Machine".[6] The Skyfire Exosuit bears a heavy visual resemblance to the Mark I ADS, and may be of this line.

Mark II ADS[edit]

The Mark II line of ADS suits vary greatly in size, design and mission, but all share a common control architecture and technology base.[1] The first of these was the Mark II [D] Geyrion, which proved out the feasibility of large combat walkers though suffered in most Earth-like climates. Nonetheless, it was successful in informing the design of future successive Mark II models, and saw some very limited use after the war.[1][7] The Geyrion ADS was online by around 2539.[8]

The Mark II legacy was later followed up with the Mark II [J] Colossus - a massive combat exoskeleton that employs a hyper-advanced neural link and reverse-engineered Covenant technology. It uses a modular weapon system though is typically deployed with an M193LP 20mm autocannon and a Mark 2555/20cm heavy railgun, alongside a SVALINN Series 02 Interim Protective Kit energy shield system - directly reverse-engineered from alien technology.[9]

Mark IX ADS[edit]

Of all of HRUNTING/YGGDRASIL's combined efforts, the late-generation Mark IX "Mantis" is perhaps the most visible. The Mantis was the most prominent combat walker employed at the close of the war with the Covenant, considered a sleek and nimble mech capable of navigating difficult terrain.[9] The Mantis includes many of the MJOLNIR project's technologies including the neural link, a compact fusion power plant and energy shield generator.[2] The Mantis has since been dispersed into many different variants;

Alongside the specialised mission packages, a number of Mantis variants are used by the UNSC specialised for various biomes. These include tundra, urban and woodland variations.


Yggdrasil is the name of the World Tree from Norse mythology.


  1. ^ a b c d e f g h Halo Encyclopedia (2022 edition), page 77
  2. ^ a b c Halo Waypoint, Mantis (Retrieved on Oct 30, 2021) [archive]
  3. ^ Halo Legends - Prototype
  4. ^ Halo Waypoint, Algolis (Retrieved on Jan 15, 2012) [archive]
  5. ^ Halo Waypoint, Prototype (Retrieved on Sep 5, 2012) [local archive] [external archive]
  6. ^ Halo Waypoint, Canon Fodder - Folks Need Heroes (Retrieved on Oct 2, 2020) [archive]
  7. ^ Halo 4: The Essential Visual Guide, page 208
  8. ^ Halo 4, multiplayer map Adrift
  9. ^ a b Halo Encyclopedia (2022 edition), page 146