The great Barrier

The barrier that The Supreme Deity has created as planet earth was separated into two planets that share the same physical space in the universe without interaction. The Barrier is anchored to the Sun and the Moon and thus is the strongest when they are the furthest apart, ie during a lunar eclipse, and is the weakest when they are the closest, ie during a solar eclipse.
When the Barrier is the strongest, any and all ties between the two worlds get severed. This means that any creature or item that relies on the magic source of the other world and would remain in the other during a lunar eclipse, Severance occurs.