The Total Codex is an ancient artifact tome, possibly created by the Callieach, that has the past, present and future written into it's pages.
It was one of the artifacts that Connacht had hidden to ensure that the dark would never be able to use. At some point in history, it ended up in the city of Covenant in the west. there it would stay, even when the city was razed during the Great War.
Following the victory against the Fallen Lord Shiver, The Legion recovered the Codex from the ruins. It was there that the Narrator open the codex, against his better judgement, and read about 'the life of a man not yet born who would resurrect the Myrkridia and visit horrors in the world without equal in history or myth', foreshadowing future events.
The Codex was then handed to the Avatara Maeldun and was assumed to be put in safe keeping for the rest of the war.
Sixty years after the Great War, the codex was once again retrieved from Covenant when Soulblighter returned. and it was during the war against Soulblighter that the man who would resurrect the Myrkridia, The Summoner, was found and brought the Myrkridia back into the world, fulfilling that foreboding prophecy.
The Archmage Mazzerin was one of the few who had learned the full knowledge of Codex and in turn transferred that knowledge to Connacht in his battle against Moagim.