What Bible says about Mormon?

There are so much details about Mormons in the internet, Is it ok to follow their doctrine? the Holy Bible ends with this authentication - 18.I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, 19.and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book. 20.He who testifies to these things says, Surely I am coming soon. Amen. Come, Lord Jesus! 21.The grace of the Lord Jesus be with all. Amen - Revelation 22:18-19

But the Mormon have their own version of Book, and its entirely different from the Bible which clearly tells the dangerous of Mormonism.