Avast Decryption Tool for Legion can unlock Legion, a form of ransomware first spotted in June 2016.

Legion adds a variant of ._23-06-2016-20-27-23_$f_tactics@aol.com$.legion or .$centurion_legion@aol.com$.cbf to the end of filenames. (e.g., Thesis.doc = Thesis.doc._23-06-2016-20-27-23_$f_tactics@aol.com$.legion)

After encrypting your files, Legion changes your desktop wallpaper and displays a popup similar to the screenshot below.