Rooting our Android devices is getting more and more difficult. The biggest change with rooting Android 6.0 Marshmallow is the need to flash a modified System image with the boot.img patch prior to installing the custom recovery and flashing the superuser.zip. Chainfire has already updated the superuser to not require flashing a system. The new update takes this a step forward. It eliminates the need to upload specific boot images for your device as the zip installer installs SuperSU in systemless mode and then continues to patch the boot.img.
The installation process still has a few steps, and instructions will vary by device. This has been tested on many devices. This is known to work on Nexus devices running Android 6.0, CM13 builds, and the S6 on Touchwiz 5.1.1 roms. If you decide to try this be sure that you first make a full nandroid backup of your device just in case anything goes wrong. Instructions can be found at the link below.
via XDA