How hould it change the game if ... ?

[Knai]

Originally Posted by NTJedi

A total razing of a castle where the walls turn to ashes would only be some high_end late game spell which is very rare and should probably have its own casting limitations such as only being casted during the summer at the cost of the casters life.

Given that this is in a province already owned, that is pretty ridiculous. If you want to raze your fortress, giving a command seems the best way to do so.