Requirments For

The Doom that Loom (Non-AC)
-Must have completed the 'Sepulchure's Armor' quest.
-Rank 10 DoomKnight (Non-AC).

The Doom that Loom (AC)
-Must have completed the 'Sepulchure's Armor' quest.
-Rank 10 DoomKnight (AC).

If The Quest Is Mix Try The Other Quest... 
I Really Can't Tell Which Is The Ac's & Non-Ac's