This build is not focusing on doing direct damage to an enemy team, rather burning them slowly and applying as many negative effects as possible. Your role is playing an Anti-Support for the enemy team. How many negative effects do you need to apply on enemies depends on the matchup. Luckily, the only rune page you will be ever using regardless what you build is Arcane Comet, followed up by Manaflow Band, Transcendence and Scorch. For secondary runes, choose Presence of Mind and Coup de Grace.

Flash and Heal - standard spells for Ashe ARAM. Don't think about it too much.

Ghost - if you're feeling crippled, you can swap Flash for Ghost but then your teammates might think they queued up with an actual bot.
Exhaust - if you want to make friends with an enemy team, use Exhaust on one of their damage dealers mid-fight and you'll have nice things said about you.
Mark/Dash - if enemy team has a Brand, hit him with a snowball to set up a 5v4.

Long story short - other spells are not as necessary.

Imperial Mandate - the item is generally good for doing flat damage. It deals raw magical damage of 45 - 75 with a cooldown of 6 seconds on each enemy champion and marks then for that time. If you have a team who can poke, peel or any teammate who can detonate marked enemies for bonus damage, you can go for this Mythic item.

Liandry's Torment - Liandry's passive burns hit enemy champions, therefore it gives you infinite mana regeneration thanks to the rune Presence of Mind. While Imperial Mandate procs 45 - 75 raw magical damage on a 6 second cooldown for each enemy champion, Liandry's doesn't have that barrier and can burn whenever you land a hit with Volley or Enchanted Crystal Arrow, which is 90% of the time. Also it deals more damage overtime thanks to Mr.200 years making everyone healthier after durability patch, therefore making them burn even stronger.

- Cutting Healing

Is their team a swarm of mosquitoes and sea of leeches?

Morellonomicon or Chempunk Chainsword - if you want more Haste and Attack Damage to empower your Volley, you can pick Chempunk Chainsword.

The reason why I build Morellonomicon is because the Grievous Wounds is applied through burning magical damage from Liandry's Torment which lasts for 7 seconds from one ability hit. How?

Grievous Wounds lasts 3 seconds + burn from Liandry's Torment lasts 4 seconds so it's reapplying the Grievous Wounds to last longer.

You don't have to build Morellonomicon for the long lasting effect but I do it just for the sake of long term negative effect. As I said in the beginning, this build is not aimed for doing flat damage.

Also, more Ability Power = more painful fat juicy mega Enchanted Crystal Arrow. 🗿


- Cutting Shielding

Life is sometimes unfair, but so is 2000+ shielding on a mother*****ng Sett.
Buy Serpent's Fang against incels who stack Shield like they shield their virginity and watch them lose it when they get penetrated by your teammates. 🗿

This item applies Shield Reaver - passive that cuts down enemy shields. Use this against enemy champions who love to frequently shield in enormous amounts such as Sett, Karma, Janna, Lulu, Ivern, Mordekaiser and ect.


- No More Hiding

Do you like the 200 years of collective experience that provide long lasting invisible champions along with Duskblade of Draktharr that makes any champion literally turn John Cena and campers who suffer from constipation in the bush? Me neither. 🗿

Buy this if enemy team has invisible champions or loves to camp a lot, Nunu & Willump for example because you can just get blasted instantly with his Absolute Zero if you were to facecheck the bush.
Oh, by the way, it doesn't work against Camouflage for some reason. So if they don't have invisible champions or don't camp as regularly, buy any other item that is acceptable to the standards for Ashe in general.


- Cutting Armor

Sometimes you get matched up against Germans who bring up Panzers from World War II to the frontline. Luckily, the mystical nation of Balkan gypsies have invented tools for stealing and tearing apart iron in the hood and other places. One of the items they invented is called Black Cleaver. 🗿

This item applies Carve, breaking armor by 5% when dealing physical damage and it stacks up to 6 times. Use this item against heavy tanks that are just impossible to penetrate ONLY if you have ADC or AD bruiser champions in your team. Don't buy it if your team is majorily AP. Use against champions such as Ornn, Rell, Leona, Sejuani, Rammus, Alistar, Sion and ect.

One cool fact about this item is that you can stack it up instantly with one AutoAttack of Ranger's Focus + Volley and you already got yourself an enemy with a fully stacked Carve of 30% armor reduction for your whole team. Ranger's Focus counts as 5 hits, therefore applies Carve 5 times in one AutoAttack.


- Spreading Disaster

If enemy team loves to stick together like fruitflies, Ravenous Hydra effectively spreads Carve and Shield Reaver as ebola spreads among african tribes so I can say with confidence they'll take social distancing more seriously than before. 🗿

Since Carve and Shield Reaver are effects both applied by physical damage, this item is insanely good at spreading them because Ravenous Hydra's damaging passive Cleave has a quite large radius.

I tried using Demonic Embrace few times and it's only good for it's burn. And since we're not focusing so much on damage, I don't recommend this.

Luden's Tempest is also not as effective when it comes to poking targets. It's a terrible option, you don't have much AP to make use of it and you need to wait a 10 second cooldown (unless you're going full AP but we're not aiming for that in this build). Also, you won't make use of Presence of Mind as much as you can with Liandry's Torment.

Titanic Hydra instead of Ravenous Hydra might sound interesting on first sight but you have to consider that you're playing Ashe with no Boots, so getting close to enemies just to spread the negative effects in a cone-shaped field of Titanic Hydra can be risky. Also, Titanic Hydra is used only on AutoAttacks, while Ravenous Hydra can be used on both AutoAttacks and abilities. Since you will be focusing on casting abilities 90% of the time, it would make sense to go for Ravenous Hydra.

Serylda's Grudge is generally a good choice. I don't use it for this build unless I don't need to buy an item that applies one of the negative effects. I don't think buying this item is necessary for additional slow but if you want to, I ain't stopping you. Use this item if enemy team has an Usain Bolt running towards you like he just won a *****ng lotto.🗿 This is good into enemies who are really fast and can chase you down with ease such as Singed, Hecarim, Skarner, Rammus, Trundle and ect.

Boots

'Ight look. The only issue with this build is you don't wear no damn yeezys. You're going to be slower than a paralyzed koala bear but your build is very powerful as you apply lots of negative effects that weaken your opponents.🗿

Just drink Elixir of Sorcery as it gives you bonus 25 true damage on a 5 second cooldown per enemy champion. Also gives AP for Enchanted Crystal Arrow and mana regeneration .

Elixir of Wrath wouldn't make much sense, the 30 bonus attack damage isn't going to make a difference plus physical vamp is useless for you.

The key is to stand behind your teammates and spray at safe distance. Watch out for champions who are slow resistant, have lots of Tenacity and are speedy.