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.
Ashe Build (it is my first build :D)
Runes - you can propably choose it better, but i think critic and damage is the most important things to grow by runes.
Skills - Dont use frozen shot on minions it is just a waste of mana. Use it only for other champions, volley you can use on minions and champions to gain some more gold, because the items you need are expensive. Frozen Shot when you will have 60 % critic will be owning because its slows and give a strong damage to enemy.
Items - Philosopher Stone is to give you mana and health regen, and GOLD! Then you buy things to make your Ashe victorious. Atack speed, Critic and damage is very important for Ashe. When you will have infinity and phantom it will gives you a strong kick of critic and speed !