So from what I can gather the darkness isn't a force or and army but the inevitable war between all things. There is no light and dark or good and evil just 2 nations, 2 queens, 2 armies and only one can rule, like the 'war' between atoms and primordial broth only one can go on and all that come after will be descendants of the winner but no matter who wins there will always be more war it is inevitable this is the true darkness. The darkness is law it's the blind law that Toland rambles about not a army or a force but law, this law is that there can only ever be one ruler one state of being not 2 or 3 or 4 ONE. And we as guardians are just the pawns of these great queens, the undead army whose only purpose is war the only choice we get is whose side we are on. This is the darkness, this is destiny.