The Greeks used Oracles and Seers quite often to help predict the outcomes of wars, battles, or even when to plant crops. The Oracle at Delphi was Pythia, a servant of Apollo. For a small offering of gold, she would consult with the gods and give often cryptic answers. If you wanted more information, more gold was needed. Medea, the grandaughter of Helios, was a seer in Greece. She assisted Jason in his quest for the Golden Fleece by using her "powers". But once betrayed by Jason, she kills their two sons and leaves Jason to his despair by flying away in a chariot pulled by dragons. 

 

There are many more examples of seers and oracles in Greek history. Some lived happily while others were persecuted for their "powers".