This is my first time making a build. Please comment on it so i can make future builds better! Ashe's build is based off of her passive and slowing attacks. The point is to max out her crit chance, give her high attack speed and high damage.

Flash: to avoid getting squished or to chase down an enemy. This is useful for avoiding getting ganked in order to stay alive longer. I would not suggest using this to chase down enemies. this should be used only as a defensive spell for ashe.
Ignite: to finish off an enemy that is running away. This will help you get early kills when in mid and on sides. Can also be used to help keep enemies from using lifesteal to its full effectiveness and get the kill off faster.

OFFENSE
summoner's wrath: improve ignite (ghost can be used as alternative)
brute force: increase attack damage since ashe's attack damage starts out relatively low
sorcery: decrease time between launching volley and ashe's arrow
weapon mastery: increase armor penetration
deadliness: increase crit strike chance
lethality: increase crit damage
vampirism: give ashe lifesteal to have her last longer in the lane
sunder: increase armor penetration
executioner: finish off enemies on low health and running away
UTILITY
summoner's insight: improve flash
expanded mind: increase ashe's mana pool for more frost arrows and volleys
meditation: increase mana regen
swiftness: increase general movement speed

Start off with Q ability
Max out W ability as soon as possible
- faster cooldown
- more damage
- great for clearing lanes of minions
Make sure to get hawkshot around fifth level to help avoid getting ganked early
Max out Q next to get full effectiveness for chasing down enemies
Enchanted arrow is not a finishing move, it is only for gaining advantage in combat for you and your allies
- stop them from using ability
- stop them from running away

Greater Mark of Desolation: increase armor penentration
Greater Glyph of Focus: increase cooldowns
Greater Seal of Furor: increase crit damage
Greater Quintessence of Desoltaion: increase armor penetration

Start off with Doran's Blade to have increased life steal, damage and health.
Then I move into getting Berserker's Greaves to help increase her attack speed.
After the boots Infinity Edge should be the first item to get. It great for increasiing damage dealt by crits, which is a must fot this build
Move into getting a phantom's dancer to give you an overall increase in attack speed crit chance and movement.
At this point, you can either get another one to finish the crit part of the build or get a bloodthirster to increase general attack and lifesteal.
For the final weapon, it depends on how the game is going. If they have high armor, get a Last Whisper for better armor penetration. If they have mainly tanks on the team, get a Madred's Bloodrazor to bring down their health quickly.
Another option for a final item is to get Trinity Force for more damage after using an ability and general inmprovements in stats. This will make sure you have 100% crit all the time.
As a final thought, if you really need more attack damage or protection, like a Banshee's Veil, you can sell the boots as you will already have a lot of movement speed from the Phantom Dancers.

PROS
She has fast attack speed so she can get off more hits
It's easy to chase down fleeing enemies because of her slowing attack
Her ultimate helps to initiate a gank attack by stunning and slowing everyone in range
She will in general deal high damage to enemies in a short time because of 100% crit with 250%+ critical damage

CONS
She is extremely squishable, meaning she will die if ganked
If you play mid, be sure to get vision wards to watch the sides for ganks
Be careful when taking a lane alone late game as you will get two hitted if they gank you

if you choose to jung with ashe at all, it will be late game, or around level 13. At this point her lifesteal will help keep you from dying and if you have sheen or trinity force, creeps will die faster this way. When in lane, be sure to get last hit on creeps for money. If you need more money, rank up hawkshot to get more money from passive for killing creeps/monsters.

When playing as ashe, her frost shot will be useful to allies to make chasing down enemies easier and to allow your allies to get more abilities off on that champion. Though not recommended until you are good as playing ashe, you can also shoot her enchanted arrows across the map to save allies from enemy finishing blows and allow them to escape. The reverse is also true as it can be used to initiate aliied attacks.

Overall, ashe should always be at the back of a fight. If she is at the front, she will be killed and her ranged slowing attacks are used to make chasing down an enemy easier. She will be infinitely useful to your allies for ganking and taking down enemies with a lot of health (tanks) with her high attack stats. She can also easily finish off enemies who have low health, like vayne. However, she is extremely squishable and will be easily taken down if you aren't paying attention. She will be two hitted by most champions and will have no hopes if ganked. If used right, she can farm easily with high attack damage from volley and other abilities, and with ignite for enemies who are close to death and getting away. be sure to use flash wisely as it has a long cooldown and she is one who needs to avoid getting hit by champions.