|“||Designed for counter-intelligence operability in the Martian territory of Acheron Fossae.||”|
The MJOLNIR/CIO variant was manufactured by Acheron Security and utilized by SPARTAN-IVs  and Counter-Intelligence Operators for Intel aquisition and strategic data conveyance deep within enemy territory. It was tested at Gdynia, Acheron Fossae on Mars.
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- Description: Designed for counter-intelligence operability in the Martian territory of Acheron Fossae
Available skins: WEB(Web), RUIN(Ruin) and RUSH(Rush)
- The WEB skin was a pre-order bonus through Amazon. It is also available in the Halo 4 Game of the Year Edition.
- The RUIN skin is available as a DLC code packaged with the CIO-armored Spartan action figure in the second series of McFarlane's Halo 4 action figures. It is not usable in Spartan Ops.
- The RUSH skin is included in the Champions Bundle. It is not usable in Spartan Ops.
List of appearances
- Halo 4 (First appearance)
- ^ a b Halo 4 Interactive Guide
- ^ Amazon.com Halo 4 pre-order
- ^ Halo 4: The Essential Visual Guide, page 148