Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Ghost and Flash are a must. YOU WILL BE targeted first, you must have the ability to get away.
Good positioning is a must... if you can't read a battle and adapt as it evolves you're as good as dead.
Stay in the back and hope you don't get stunned.
Last hitting and spam volleying creeps is required since money is one of the most important things to go after in a game.
Ashe's ability to slow down a whole team with volley, single enemy with frost shot, and stun multiple opponents with Enchanted Arrow makes her a great supporting character. Always take full advantage of these skills.