I just focused on tell you the basics.

Skill build:

This skill build is configured to maximize Focus Fire (especially for mid game). Because of this, we take FF at lvl 10 and 11, and max shackleshot early for the 3.75 seconds of stun (that we'll be using to get lots of damage with FF).

1. Powershot
2. WindRun
3. PowerShot
4. Windrun
5. PowerShot
6. Windrun
7. PowerShot
8. Windrun
9. Focus fire
10. Focus Fire
11. ShackleShot
12. ShackleShot
13. ShackleShot
14. ShackleShot
15. Stats
16. Focus Fire
17... Stats+...

You need windrun for survival and powershot for damage deal

Item Build:



Phase Boots (1500 gold)
Diffusal Blade (3300 gold)
Cranium Basher (3100 gold)
Aghanim's Scepter (4300 gold)
Orchid (5025 gold)
Monkey king bar (5400 gold)

Order:

blades of attack+tango+clarity
blades will help you last hit creeps
than make phase boots so you will have +24 dmg

Late game:


Q: Why these items?
A: If you play vs skeleton,medusa or any inelegence hero with your ulty you will drain his mana very fast and bash a alot even if you are range you got imba attack speed.

Q: why not treads?
A: You got enough ATS so you need damg


lvl 1 - 50 base (hp - 435)
lvl 7 - 65 base (ff1 - 325) (hp - 720) 8 seconds.
lvl 10 - 73 base (ff1 - 365/548) (hp - 853) 9 seconds.
lvl 12 - 78 base (ff2 - 468/702) (hp - 948) 7 seconds.
lvl 14 - 83 base (ff2 - 498/747) (hp - 1043) 7 seconds.
lvl 16 - 89 base (ff3 - 623/935) (hp - 1176) 6.5 seconds.
lvl 18 - 94 base (ff3 - 658/987) (hp - 1347) 7.5 seconds.
lvl 25 - 112 base (ff3 - 784/1176) (hp - 1955) 9 seconds.


Skill guide: PowerShot
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When you're harrassing, try to get the full damage on the hero, please. Its worth it.
Other than that, you just need to familiarize yourself with using it.
The animation is really awkward, can't be cancelled, and I suspect that it takes more than a second to fully cast. If you order a command before it channels completely, it does half damage, but still travels maximum distance. Its very hard to tell when it does half damage because the animation is exactly the same, and it still takes a while to finish. In order to prevent this, Shift Click to move, since you can't cancel the ending animation anyways.
Get used to and abuse its maximum distance - if it goes through creeps or trees the max distance is lessened.

Tip 1: There are times when you want to make the cast time shorter - for instance, if someone is getting away with just a sliver of health, or if you're scouting. You don't have to wait the full second.
Tip 2: Its also somewhat useful for farming neutrals, although I'm not exactly sure of the best way to do this. Pull the neutrals so you can hit 2 camps, and finish off the rest with your good attack damage.
Tip 3: On smart escaping heroes, press 's' instead attacking and see which way they dodge, and then shoot them.


Skill guide: ShackleShot
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No casting time, so a good idea is to issue an order immediately after it shoots (ie, move closer to the enemy, Focus Fire, or run away). This helps in maximizing the stun time.
You need to get familiar with its quirks - Expect to play 3-4 games before you get comfortable with it.
You can creep aim a ShackleShot to get extended range or a surprise stun. Creep aiming is targetting a creep to get ShackleShot off.
As WindRunner, you'll want to memorize/get used to the timing of creep waves, if you haven't already. ShackleShot the hero as the next creep wave is coming in from behind, and chances are you'll hit. This is very useful for chasing, too - don't just ShackleShot out of instinct, but follow until the hero meets the creep wave and shackle.
Hitting 2 heroes with ShackleShot requires good reflexes and a bit of luck. Just always be on the look out for badly positioned heroes.


Skill guide: Focus Fire
=================================
Its really point and click, but you can waste it by positioning wrongly or not using it right after a stun. This is THE crucial skill to get to know - first in how to maximize its damage, and second, how much damage you will do.

Knowing how much damage your ultimate does at all times is really, really crucial - this defines how good you are with WindRunner. Knowing this makes your ganks successful and opens up many more opportunities to gank others.

In general, it is not good to use Focus Fire before lvl 11 because you don't have 3.75 seconds of stun time and your damage isn't the best.

Memorize this for Windrunner!!!
A conservative estimate of the range of people that you can kill based on how much time you get and how much damage you do:
* = Focus Fire lvl 3.
Armor values are 40% and 20% (11 and 4 armor, respectively).
Incidentally, you can see why a deso is so effective on her, which I have yet to consider how to add in.

2 seconds of stun:
+30 dmg: not worth it
+56 dmg: not worth it
+80 dmg: 320-432hp //atk + powershot instead
+100 dmg: 370-490hp //atk + powershot instead
+120 dmg: 410-550hp
120* dmg: 478-640hp

3 seconds of stun:
+30 dmg: 360-480hp //atk + powershot instead
+56 dmg: 450-600hp //atk + powershot instead
+80 dmg: 540-730hp
+100 dmg: 612-810hp
+120 dmg: 680-910hp
120* dmg: 800-1064hp

4 seconds of stun:
+30 dmg: 480-640hp // barely worth it
+56 dmg: 600-800hp
+80 dmg: 720-960hp
+100 dmg: 820-1090hp
+120 dmg: 910-1220hp
120* dmg: 1026-1370hp

Tip 1: Use it right after a ShackleShot. This gives you 3-3.75 seconds. If issue Focus Fire before the stun hits, you get the entire stun time for damage.
Tip 1b: WindRun+Return and run up to them to get off the ShackleShot if needed. Be a man.
Tip 2: Use your WindRun to slow them down. This can give you another 2-5 seconds, or 6-15 shots.
Tip 3: Kill Roshan! While she's not the best for Soloing Roshan, she dps's him like no other.
Tip 4: Use it on the tower if you are taking down a tower.
Finally: Don't be afraid to 'waste' it on someone who's has yellow HP! That hero is better dead than alive casting spells everywhere.

Orchid:
=================================
Why not? The Orchid needs some explaining because most people use it incorrectly anyways.

Contrary to popular belief, it is rarely needed for the extra 20% damage. If you know your Focus Fire damage well enough, you know that you won't need it because they'll most likely be dead already with your dps.
The best thing about it is the 5 second silence. Its a beautiful counter to soooo many things if you're fast enough and are observing the battle. It breaks chain/team stuns - that's the best use of it - but also can make spammers, blinkers and even carry heroes defenseless and over exposed.
So - use it for the silence, not the extra damage.

Skill guide: Teams
=================================
WindRunner excels at 1 on 1 - but Dota is a team game. Damage calculations just show her potential - in 2v2 or bigger, it doesn't always work that way.
If you're ganking 2 people (with a friend!), you can still get a good Focus Fire if you stun both of them with ShackleShot. Unlike channelled spells, Focus Fire doesn't get cancelled - so you can still attack the other person if you get stunned.
In big team battles, you don't have to get into the middle of a fight. For the most part, sit back, look at what's happening, PowerShot, save ShackleShot for disruption or to dual stun opponents. Your attack + move is good so use it - you should be very used to it by now (since your entire farming career is just that). She's not built for team fights, but she does a good job and isn't easy food.

Game Play:

Early Game:
Grab your preferred items and go into a lane.
Start harrassing enemies with PowerShot at lvl 5. Don't use PowerShot to mindlessly hit creeps - use it to hit the opponent with the full 280/360 damage. You have a decent attack animation to last hit...

Really try to hit the enemy directly with PowerShot. Shoot it from out of sight - 1200 range. Shoot it from the fog of trees. Just get the full damage on the hero, please!!! This is her strength and not using it a big waste.

Go for the BladeMail first, and then either the Phase Boots or a Force Staff. You can skip the Force Staff if you want to just start on the Orchid - Force right now is just fun or if you like to pull off crazy manuevers for replay value.

Mid Game:

If you have around +60-80 damage and have lvl 2 ff, you can go hero hunting or ganking. However, this is mana intensive - so if you are on the hunt, be prepared to go back to base often. Its good if you can kill someone, use your bottle to farm a neutral camp while returning home, recharge, and go find someone else to kill.
Note: Go with a partner. Just one friend with any kind of stun is worth +600-1k additional damage of Focus Fire, not to mention his own damage.

If you are in a lane -
1) last hit everything with your good damage. Never waste mana.
2) watch the map.

Its good to have at least 600 mana at all times, so keep track of your mana pool. Always plan to go home to recharge your mana if its low.

Try to participate in everything. Be where you're needed - be in every team fight and participate in ganks as often as possible.
Don't farm too much - Alleria is a great partner for mid game hunters, stunners or nukers. She has a lot of skills that make it hard for enemies to escape, and with her damage output she gives them a good reason to run.

Use Focus Fire and be surprised. This build makes it quite awesome at all times. And go after Roshan sometimes, too.

Late Game:

By mid-late game, you should have your Orchid. If you feel like the game is going to go on long, try to farm up aganims, as her Focus Fire needs to be primed and ready at all times. Afterwards, go for cheap damage like a crysalis.

In late game play defense in team battles. Your job is to sit back and watch how the team clashes are going while spamming your spells. Make sure you use Orchid for the silence, not the amplify. Also, save ShackleShot for defense and not for initiation, unless you're catching stragglers who are over exposed. Be chicken until you have a good opportunity and then Focus Fire the enemy carry.

Yes, your prime role is to kill the enemy carry. The worst thing that you can do is die before you get a chance to Focus Fire. Besides, people shouldn't be targetting you because you're not exposed, have good escape mechanisms and are not easy to take down.

You also have decent damage to take down towers even without Focus Fire - so try to stay alive for the cleanup. With Aganim's you can be really, really powerful as a cleanup tool.


Examples:

Here I will show examples of the complicatedness of Windrunner. /todo

Q: What are some good teammates?

Rhasta - it can hex or shacle someone why you got your focus fire, and bith are good for towers.

Trax- it got damage aura + slow.