Music to Accompy you throughout this article
The story features two or more Big Bads, each of whom has their own distinct agenda and resources. The result can vary in posibilities but it may be the case that none of the villains have anything to do with each other. Played straight, each Big Bad should be of a comparable threat level to prevent one from overshadowing the other.
Having multiple main villains can bring new dimensions to the story and make it more complex and less predictable. It can force The Hero to face a range of different challenges, for example if one villain seeks to Take Over the World while another is a more personal enemy from his past, though it's possible for both to have identical goals without making the story any less interesting.
The success or failures of one Big Bad can affect the fortunes of another as they may have to consider each other in their plans, or might try to profit from another's defeat. The hero might defeat one villain before fighting another, or might regard one as more dangerous or important than the others. If all the Big Bads are equally powerful and dangerous - or inverted, if some are more powerful and/or more dangerous than others.
There the Rival who's been gathering an army of loyal followers and also has been contacted by someone for as-yet-unknown purposes Invloved.
Another is the Bigger Bad of the story He is one of a group of Cosmic Abominations. One Villian is also trying to harness his power, Another wanted to destroy/usurp him, and Someother Bad Guy is trying to collect him to teach the world its madness. Mr. Big Good appears to wanted it recaptured, but with him it's very hard to tell.
As One Villian puts an Asecendant of commission, the Arch enemy turns Good, The Power Behind the throne forms yet another duumvirate with his resurrected ancestor, and the two of them succeed in summoning the Bigger bad.
Man Hope this story dosen't get too complex.