A young boy known as the Avatar must master the four elemental powers to save a world at war — and fight a ruthless enemy bent on stopping him.

A group of vigilantes known informally as “The Boys” set out to take down corrupt superheroes with no more than blue-collar grit and a willingness to fight dirty.

The Targaryen dynasty is at the absolute apex of its power, with more than 15 dragons under their yoke. Most empires crumble from such heights. In the case of the…