Don't think that magic power erosion only happens to people from Earth. For the people of the Otherworld, hearing about this disease also makes them change color in horror.
I mentioned before that the bodies of Earth people are like solids. Thus, magic power would constantly attempt to break through the surface of their bodies to achieve a balance with the atmospheric magic power. It's somewhat similar to atmospheric pressure.
Once magic power breaks through the surface of an Earth person's body, it will damage their organs and ultimately cause organ failure. Even worse is that this process is almost irreversible. Meaning, once an Earth person suffers from magic power erosion, they can only wait for their inevitable death.
Given the above standards, magic is almost deadly for Earth people. Even the most basic healing magic could potentially kill an Earth person in their prime.
