A harder VM designed to train for both pentesting newer IT infrastructure methodologies as well as network pivot practice.
You'll need to be familiar with pivoting techniques, web app vulnerabilities, Metasploit and Meterpreter, as well as enumeration methodologies and a good bit of patience.
As a note, there are two additional bonus flags that will appear in the /root directory based on pre-defined actions taken during the course of rooting the VM.
VulnHub