I think it says in COG that all the Malkioni orders' grimoires are derived from The Abiding Book. Yet, there was much powerful sorcery around prior to the AB. Was this sorcery substantially different from the grimoires that we know today? Arkat's sorcery, for instance, pre-dates the AB by a long way, so would Stygian sorcery be fundamentally different from Malkioni sorcery?