Sona is a support. She's the best harassing support in the game. I started ADCing, but I liked the harassing part rather than the last hit part. Sona let's you sit there and poke at people basically the whole game. She's a little squish, but if you max her Q early she puts out real damage early game and can set up very epic confrontations. Mid game you can use her Ult to help gank or trap opponents. Late game you use your ult to blast their team and win the fight.