The "Incl. ALL DLC" tag typically means it includes the Survivors of the Void expansion, which added the Railgunner and Void Fiend survivors, the Simulacrum game mode, and various new items and stages.
Always scan .zip files from unofficial sources with updated antivirus software. File: Risk.of.Rain.2.v1.2.4.1.Incl.ALL.DLC.zip ...
Files with this naming convention are often found on third-party distribution sites. If you are preparing to install this: The "Incl