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.
So this is a pretty basic ashe build. This build is based mostly off of a mid lane Ashe. Some items would need to be changed depending on who you're against. Sometimes it is better to go for attack speed first (if you're not farming enough cash), and sometimes you'll need a madreds (if nobody else is building it).
As for spells, I personally chose ghost and clarity. I enjoy the clarity in the beginning/mid game for using my skills as much as possible. And ghost is a good way to run (fast) in or out of battles (usually out with ashe). Other great spells would be teleport, ignite, and flash. It all depends on your playstyle.