[@Klomster]
That's not possible. You cannot usurp red gods since Redgods don't actually have a 'seat' to usurp -- they are categorized as seatless deities. And Red Gods don't have celestial servants of their own, only mortal ones. But mortal ones can't interact directly with Redgods seeing those are in the Celestial Plane, and mortals in the Material Plane. At best your mortal could have lured the Redgod to enter Materia in an avatar form, and then kill the Avatar. But that doesn't guarantee a god's death. Perhaps the Avatar was lured to the world to BE the Sacrifice? Because if that's the case, there'd be some possibility for your mortal to being a Redgod himself.

Also I do insist you do take a spot on the map as to where your army is currently settled. It doesn't have to be a nation but merely a geographic region, only home to nomads.