A Monument to All Your Sins
From Halopedia, the Halo wiki
A Monument to All Your Sins (capitalized A Monument To All Your Sins in Halo: The Master Chief Collection) is a Campaign Achievement in Halo: Reach and Halo: The Master Chief Collection. This achievement is awarded when a player completes every campaign mission in Halo: Reach on Legendary solo. It is represented by a Legendary symbol with a human skull rather than the traditional Sangheili skull.
- The achievement's name is derived from a quote from the Gravemind: "I? I am a monument to all your sins."  This line is also said by Cortana while under the influence of the Gravemind.
- This achievement has somewhat the same icon as the "Hired Gun" achievement from Halo 2 for Windows Vista.
- Completing the Campaign on Legendary will also award the "Gods Must Be Strong" Achievement, which does allow for co-operative play.