Scripts

Won't it be too powerful for the heroes? After all, the plague kills a fairly large percentage of the total number.

Maybe errorHook would be suitable?
void errorHook( fCallback )

Allows you to set an error interceptor. By default, when a script error occurs, the current thread terminates. Thanks to this function, you have the opportunity to adjust this behavior – before stopping, control will be passed to the fCallback function.
Found it at Novik's. If this doesn't help, then there are no more options.