The third class to be unlocked at Reveal.Diablo3 is the Monk: the master of martial arts, mantras and channeling all that is holy. As it is the tradition, a spotlight video accompanies the unveiling of the Ivgorod monasteries' disciple.
This is also your chance to create an unique Monk banner that will give you that cool in-game sigil when Diablo 3 launches.
Source: Reveal.diablo3.com
