We don't highly recommend rooting your smartphone but most Android developers and geeks who know what they are doing will be happy to know that the Nexus Root Toolkit version 2.1.1 is now available. This one features full Android 6.0 Marshmallow automation. It also takes advantage of TWRP’s adb root shell. instead of the old modified boot.imgs.
The developer Wug Fresh also adopted Chainfire's autopatching systemless root method so you know this root tool kit is made more efficient for everyone. As with most updates, bugs have been fixed and Nexus Player scripts were updated.
Nothing wrong with modding your device but if you want to do such, you have to know how to properly do it. Good thing there is the Nexus Root Toolkit that makes modding convenient and much easier. The app for Windows lets you unlock, root, and flash freely and safely.
This version boasts of full support for Android 6.0 Marshmallow but please note this is just a minor revision and not a major app update so don't expect too much. The developer may still be working on a big one--a major update- but for now, this will do. Let's just wait for the next version to be released.