18 I warn everyone who hears the words of the prophecy of this scroll: If anyone adds anything to them, God will add to that person the plagues described in this scroll.

Read Revelation 22:18 Using Other Translations

For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:
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,
And I solemnly declare to everyone who hears the words of prophecy written in this book: If anyone adds anything to what is written here, God will add to that person the plagues described in this book.