During Planet X’s first pass, the Earth was moved into its current orbit, closer to the sun than it was originally. Subsequently, when Planet X enters the inner solar system around every 2,000 years, it only comes as far as the asteroid belt, but it scatters a lot of asteroids around, and some of these impact Earth.
One of these Planet X-related asteroids may have caused the destruction of the ancient Sumerian empire. There are numerous coded references to Planet X in the Bible, such as the trumpet judgments in Revelation, as well as in the Genesis flood narrative; he also contends that the Star of Bethlehem was actually Planet X.