Reflexil
The .NET Assembly Editor
Reflexil is an assembly editor and runs as a plug-in for Red Gate's Reflector, ILSpy and Telerik's JustDecompile. Reflexil is using Mono.Cecil, written by Jb Evain and is able to manipulate IL code and save the modified assemblies to disk. Reflexil also supports C#/VB.NET code injection.
Homepage: http://reflexil.net Howto: http://www.codeproject.com/KB/msil/reflexil.aspx Video: http://bit.ly/kill3rv1d
Download here: https://github.com/sailro/Reflexil/releases