Augury is the art of divining the future in some form or another with magic and those who specialize in using it exclusively are Augurs.
Augury is an immaterial and lore oriented school of magic, and a surprisingly powerful one too. The very act of seeing a future event makes that event much more likely to happen, even if the universe has bend over backwards to make it happen. Trying to avoid the foreseen event tends to create a backlash of some kind, so Augurs have to be careful with what they want to see and how. By being vague, they can leave more wiggle room for how an event will happen.