If the player has the Against Some Odds [ihrb.wikia.com]achievement, then they can use Rambro. This achievement is not too hard to get, and can theoretically be unlocked within the first several hours of playing the game. However, it's better to wait until you have more experience, as beginning players may not be accustomed to the sudden addition of curses to their play sessions.

Character wiki page - http://ihrb.wikia.com/wiki/Rambro