Resolved issue, figured it out from creating dumpfile of rundll in windows which led me to figuring out the dll file that it was looking for. Removed following from dll.xml and issue is fixed.
<Launch.Addon>
<Name>Migration Tool Plugin</Name>
<Path>MigTool.dll</Path>
<DllStartName>module_init</DllStartName>
<DllStopName>module_deinit</DllStopName>
</Launch.Addon>