Corruption

Corruption is a destructive force that is assumed to have originated in the Wardlands. Corruption operates by altering and warping things it comes into contact with and turning them into different maladaptive versions of themself. Corruption can present very differently in different Wards and worlds, but it always results in a change that is worse for what it comes into contact with. Left unchecked corruption will slowly seep from its source and impact a greater and greater area. Corruption is known to work at different speeds under different circumstances. Some wards have been taken over by fast corruption seeps in a matter of days or weeks, while others have slowly been corrupted over the course of years or decades. 

Corruption can only be reversed and repulsed with magic.