Behind the scenesEdit
In reality, the labarum was an introduction by Emperor Contantine I around October 27, 312, preparing for the Battle of the Milvian Bridge. It represented the Greek letters ΧΡ as the monogram for Christ (in Greek: ΧΡΙΣΤΟΣ) and was adopted as a Christian symbol in traditional Christianity (Greek and Latin).
The Emperors identified themselves with the Mithraic title Sol Invictus, but other than that, the labarum was never historically linked to Mithras; and certainly the Romans who brought the worship of Mithras to Britannia were not the same Romans of Contantine I.
The appearance of the labarum as the symbol of Mithras in the game is perhaps a misconception by Christy Marx or a pseudohistorical misinterpretation.