This is unlocked when you reach level 10 if you have picked one of the "healing" types. I started as a sorcerer. Once you reach level 10 and if your achievement doesn't unlock in game simply back out of the game and restart/ log back in. (I had to start another game so I would disconnect from the servers). If you log back in with the character you have reached level 10 with, this achievement will unlock as you load in.