A dark, sinister agent tears apart once inseparable brothers into fierce, hateful rivals as he plots to destroy the protagonist and his family for opposing his rule as a demi-god on ancient Earth.

Maybe you could try something like this:

When a demi-god tears a loving brother from his family, he must find a way to destroy the rule the demi-god has over ancient Earth and reunite with his family.

I was just going to ask 'Who's the lead character?' but dpg basically beat me too it.

Once again, the logline makes the mistake of defining a plot in terms of the antagonist. ?A plot in a logline ?should be defined in terms of the protagonist.

(And the tag "protagonist" should not be used in a logline.)