It's a security framework that can be very helpful in performing all the five phases of attacks including reconnaissance, scanning and enumeration, gaining access, escalation of privileges, maintaining access, and covering tracks. Apart from that it also contains a set of tools targeted for web developers and code debuggers which makes it handy for both offensive security and defensive security related tasks.
Mantra is design to be lite, flexible, portable and user friendly with a nice graphical user interface. You can carry it in memory cards, flash drives, CD/DVDs, etc. It can be run natively on Linux, Windows and Mac platforms. It can also be installed on to your system within minutes. Mantra is absolutely free of cost and takes no time for you to set up.
You can download Mantra 0.6.1 here:
Windows – OWASP Mantra Security Toolkit – Gandiva.exe
Linux 32-bit – Mantra Security Toolkit – Gandiva.tar.bz2
Or read more here.