I know what you might be thinkin this is his first build so it has plenty of mistakes, but trust me with this build i was on a 10 winnning spree (until i got bored of playing) not even they OP champion Yi couldnt beat me so lets get right into the build shall we and hope you guys are as skillful with Ashe like me :3

For runes I was going for critical, armor penetration, and attack speed, mana and mana regenration (because all of ashe attack cost alot of mana but not to much) with these runes is is possible to take down the opponents team even though you might be losing or your team is cooperating

This is a very important part of the game "Masteries" this is an important part of your game because when hey think that your a weak player the is a game changing experience witch leaves them to basically get armor, so this is very important to get armor penetration and attack speed

So basically what you need is attack speed, slowing the enemy, armor penetration, and criticals.
If you really want an easy kill follow these steps on how to build your game, so you need attack speed witch will complement movement speed and critical hits because Ashe has frost shot will do the rest to beat the enemy.

These Masteries ignite and ghost are a really offensive summoner spells these are useful for when you have an assured kill, and ghost is a complement for ignite because Ashe basic attacks slow the opponent and ghost gives you an extra boosts for your attack

Skills are very very important to Ashe because if you have skills, learn the weakness of your enemy it will be way easier for you to make a pentakill, i know you might think pentakill is impossible for you and not useful. But with this build you will be basically immune to deaths witch is GREAT¡¡¡¡¡¡¡¡¡¡¡¡ :3