Why Does The Decay Not Stop The Corruption?

If the corruption is created when light and dark battle, shouldn't the decay, slowly making gavel dark, stop the corruption, as gavel will have become dark, meaning there is no light for the dark to battle, and no war between them, therefore stopping the spread of the corruption

 

The decay isn't darkness, it's another form of battle between the light and the dark. That said, it might stop the corruption as it might observe some sort of armed truce with the corruption.

 

The decay isn't the same as the corruption except for being exactly like the corruption in pretty much every way.

 

The decay is a disease caused by the clash of light and dark in Orphion, the light incarnate, slowly fading Gavel's light away

 

also the corruption is in Wynn whilst the decay is in Gavel, and they can't spread over the sea unless someone brings it over so there's no way of them meeting up any other way

 

Note that Corruption is only in Wynn Province and Decay is only in Gavel.