No need to reinvent wheel. StyleCop already does this.

It also allows for user rules. For example detecting the Activator usage should be rather easy to do.

There is also ReSharper into which (in addition to being extensible on its own in a similar way) can integrate StyleCop directly into Visual Studio, so the analysis can be done as the programmer types the code without having to manually launch a separate tool to check the conventions.

StyleCop can of course also be launched on its own via GUI or from command line (so integration into whatever build system/CI you are using is possible).

No need to reinvent wheel. StyleCop already does this.

It also allows for user rules via extension API. For example detecting the Activator usage should be rather easy thing to do (however detecting legitimate usage of Activator may be very non-trivial task, but that would apply to any code analysis solution).

There is also ReSharper which (in addition to being extensible on its own in a similar way) can integrate StyleCop directly into Visual Studio, so the analysis can be done as the programmer types the code without having to manually launch a separate tool to check the conventions.

StyleCop can of course also be launched on its own via GUI or from command line (so integration into whatever build system/CI you are using is possible).