Can someone explain to me this item on Ashe. I assume it isnt first pick anymore due to her passive but is it worth getting at all? I am a little confused and could use some clarity.
Give me a good example build if you are ahead (late game) would be nice also. and explain why you chose what you did. If its too much, link me to a solid guide if possible.
Can message me in game as Wan2play
What about it do you not get?
it just buffs her minicrits and slow.
Yes its still worth getting. The current standard core ashe build is : 
.
Afterwards, you could go 
(note that these last 2 items can be swapped out for more situational items)
The reason infinity edge isn't being rushed as a first item is because its not the most gold efficient build path currently. Players rush essence reaver because it gives both crit and cooldown which is useful for casting more ashe ults. More importantly, its cheaper than IE which makes it a better early game buy. The attack speed item afterwards speaks for itself. You build IE as a 3rd item because it'll gives you more damage out of any other AD item buy.
Ashe's passive likes crit strike and crit damage, so IE really helps her do more damage. However, it isn't the best first item because it's expensive and the way it interacts with her passive gives more of a boost if you have more crit.
For example, if you have 40% crit strike, her passive does 40% more. If you have 50% crit damage (like from IE) it multiplies all crit strike by that much, then adds it in. So if you have 40% crit strike and 50% crit damage, you do 60% more damage.
So IE gives you a total of 30% more damage (20+.5*20) whereas ER gives you 20% more damage and 10% cdr. But once you get both, you have 60% more damage and 30% cdr. Getting a hurricane and some lifesteal and pen and you have yourself a fairly basic, but deadly, adc build.
The passive of IE does work with Ashe's passive. Basically, what Ashe's passive does is say that instead of having spiky damage based on when she crits or doesn't, she just has "perfectly average" damage + 10%. (except for the first attack if you don't apply frost with an ability) The IE passive will give her the same damage boost that it would on any other marksman on average over time.
I assume it isnt first pick anymore due to her passive
You assume wrong. IE works perfectly fine with Ashe's passive. Ashe's passive is made so that she gets the same increase in DPS from crit that everyone else does. If someone else would be getting an average of 40% more autoattack DPS from having crit, then Ashe just will get 40% more autoattack DPS from having crit. She also gets increase in crit damage just the same as everyone else does.
When thinking about Ashe and crit, you don't really have to take her passive into account at all. Mathematically, it works out to be just about the same as if she didn't have it (disregarding the extra 10% and her first hit).
