Hello there everyone!

I'm Answer, rank 1 Europe player, doing my best to get to the TOP of the MMR and Ranking!:)

I wanna introduce you my Brightwing build (s).
Brightwing is my main support, and I tend to win most games with her (nowadays).

Brightwing is one of the greates supports (by my meaning). She brings a lot of utility for her team from the beggining of the game, till the end. AoE healing with her passive, Soothing Mist, healing all wounded allies around her, turning enemies in to the animals and jumping from ally to ally to heal them and also, quickly escaping from the enemy! Brightwing is positional hero, however, her utility allows her to get closer to the enemy (depends on who is she facing) and getting quickly back to her original, and thus, right position. She's extremely worth for team of any kind, as she can blow up her enemies right to the face of her own team, and then, the Hell can be unleashed, and enemy team can be literally removed! Brightwing is able to be played in many ways, and as I listed, I play her with 3 builds, depending on my team composition, map and tactic. If you get in right shape with Brightwing, you can turn around many games in your favour.
I play Brightwing either as a fully utility support - Which gives your team mates powerful shields, fast Mercenary Camp cleaning and additional healing with your passive!
Another build I use to play is passive - Passive build for Brightwing is based upon her healing ultimate, which gives her ability to rapidly heal her allies, and also quickly escape and "teleport" from ally to ally, and gives Brightwing full potential of her Pixie Dust, which can save a lot of lives!
Last build, the aggresive one - Is for dishing out damage, blowing up enemies in to the face of your own team (or vice versa) and making them vulnerable, when turned in to some cute critter!
Also, important to mention is build that covers half things of passive and utility things, and the second half is for aggresive, yet still utility things!

Brightwing is trully a lot of fun to play and one of the cuttest heroes!

Brightwing has a lot of utility stuff, as well as damage dealing, and each of her skills bring some "fruit" for her team in game!

(Q) Arcane Flare is Brightwing 's AoE damage dealing ability and, thus, her main scource of damage. This ability hits harder if you hit your enemy with it's centre, so, this says that if you have heroes in your team that have a lot of CC, like Uther, Tyrande, Malfurion, Arthas and so, this ability becomes more potential. Thing to mention is, that this ability does AoE damage, and you might be lucky and skillful enough to hit more opponents with it's centre. Sometimes, it can be very difficult to hit someone with the centre, but if you do so, you will be surprised how much damage this ability can do.
This ability is for aggresive purpose.

(W) Polymorph is Brightwing 's utility ability. One of the greatest disablers in the game. It immediately interrupts any channeled ability (except Diablo 's) and does little bit of damage. This ability is just awesome, as it can save your allies, or give you a free kill. If you can get right moment of casting Polymorph, for example, when Sylvanas uses her Haunting Wave, and you get right moment of casting Polymorph, she won;t be able to escape, thus, then she will be easy kill for your team. Saving Polymorph for hard channeled abilities, like E.T.C. 's one or Nazeebo 's is key for winning TeamFight.

(E) Pixie Dust is Brightwing 's passive and utility ability. It enhances your teammates (or yourself) with a protective shield (mini version of Block) and a little Speed Boost. This ability is great for escaping from enemy, or vice versa, trying to catching them. For example you cast Pixie Dust on E.T.C., giving him another stack for his Block ability plus the movement Speed Boost allows him to get faster to the centre of enemy team to channel his ultimate. With talent Anti-magic Powder, you will turn your Pixie Dust in to the Spell Shield version aswell, making it even more worthy!

(R) Blink Heal or Emerald Wind are Brightwing 's ultimate abilities. Each of them have completely different use. Blink Heal is fully passive and utility ultimate, teleporting you short distance to ally, and instantly healing them. This ability is also great for escaping, as you can teleport yourself to friendly minion aswell.
Eemerald Wind is utility and aggresive ability. It creates expanding nova, that damages enemies, and knocks them back. This is great with combination of Sprint, as Brightwing can Sprint before the enemy team, use Emerald Wind and "throw" enemy team in to the hands of her own team, or, it has utility effect, which knocks back enemies, saving your allies. Damage of Emerald Wind is valuable, so it might causes some troubles to squishies in enemy team.

Brightwing does not use mount. She uses ability called Phase Shift, which teleports her to allies hero on the map with decent cooldown. Pretty good while playing on big maps like Cursed Hollow / Sky Temple.

Soothing Mist is AoE passive healing of Brightwing. Brightwing heals each few seconds allies around her for moderate points. This ability is just great, as the AoE heal ensures you that your allies have better chance for survivalability. Talents like Regenerative Rains and Gust of Healing causes even more heals from Soothing Mist, as in passive way, or in active.
Soothing Mist is clearly passive and utility ability and scales well with all shields, heals and healing over time abilities.

So, depending on build you want to play, Shield Dust and Bribe are far the best picks from this tier for Brightwing. Shield Dust essentially enhances your Pixie Dust, and gives it full potential to become a simple Block with some movement speed, which is totally awesome. Bribe is very good map control ability, which allows you to defeat maximally 2 mercenaries immediately. This is worth on maps, where are many mercenary camps, like Sky Temple, Cursed Hollow, Blackheart's Bay and so. Both Bribe and Shield Dust are worth as for passive, so for utility build.
Arcane Precision is pick only for aggresive build, thus, if you cannot land well Arcane Flare, or your team does not have a lot of CC, so you cannot guarantee centre hit, just skip this one if you feel so.

So for Brightwing, there are 3 clear picks. Envenom is awesome for aggresive build, as it can dish out very much damage, especially in late game, and it is very useful against squishy targets like Jaina and Nova.
Anti-magic Powder is for passive build mostly, and it enhances your Pixie Dust, so it might become a lesser version of Spell Shield. This stacks greatly with Shield Dust and it is extremelly useful when you want to safe an ally.
Protective Shield is great utility thing, that helps you and your allies to survive bigger bursts or last blows. The shield amount is increased with the time, but sometimes, I just preffer more Anti-magic Powder over Protective Shield, as Pixie Dust itself does not have such as long cooldown such as Protective Shield, so it might save your allies and you more often.

Within this tier, I pick mostly, for 99,9% only one talent here for Brightwing and that is Gust of Healing. It enables your trait, Soothing Mist to become active, and each second for few seconds release healing waves for you and your allies. This talent is very viable for all builds, as you heal with Brightwing with her trait all the time, no metter what. Regenerative Rains is also possible pick, but it is much weaker then Gust of Healing, even though that Gust of Healing has some cooldown after it's activation, Soothing Mist will continue healing.

These both ultimates have totally different use. Blink Heal is excelent ability for fast healing and for fast moving during fights. Heal is very solid and cooldown is short, and it holds 2 charges. Blink Heal is great for any build, depending on your team composition and so on your enemies.
Emerald Wind is used for both, offensive and deffensive choices. It's damage is solid and the knockback utility is just awesome, you can save your allis thank's to this, but also, you can blow up your enemies to the face of your allies, while enemies are desoriented, so it's easy to kill them. Emerald Wind is great for all builds.
Besides Arcane Flare, Emerald Wind is Brightwing 's main damage dealing ability.

Brightwing is very versatile hero, when we talk about her movement. Thank's to things like Pixie Dust, Blink Heal and so, but Sprint is something of a great utility thing to pick. It can be used for both, offensive and deffensive purposes. For deffensive, you clearly activate Sprint to escape your enemy, or to help you allies, but for offensive, it's excellent, especially combined with Emerald Wind, as you will fly fast behind your enemies, activate Emerald Wind, and blow your foes to the faces of your allies, meaning that your team will be able to kill enemy team very fast.
Sticky Flare causes your Arcane Flare to apply slow (AoE) on to your enemies. Since this slow is AoE, it is very worth for chasing or escaping enemies. This is better combined with heroes that have gap closers ( Illidan, Kerrigan and so). Both, Sprint and Sticky Flare can be used for utility, passive or aggresive builds.

Brightwing 's best utility thing is in Polymorph and so, with this tier, you are able to choose between Sticky Powder, which reduces the movement speed of Polymorphed target, which is extremely worth, especially if you have for example Diablo in your team, he will smash his targets towards your team, and Sticky Powder will take care that the target won;t escape far.
Another possibility, Critterize, increases damage that Polymorphed targets take. This stacks well with, for example, Tyrande 's Hunters Mark.
Both Sticky Powder and Critterize are great utility things and they just rock.

Most of the time, I pick Rewind for Brightwing, since it allows you to cast more Pixie Dust and Polymorph, which is absolutely awesome. Storm Shield is great for utility build, as it stacks well with Protective Shield and Blink Heal.

Also, to mention, Continuous Winds are great not only for aggresive, but also for utility reasons, as you keep pushing back your enemies, confusing them and your allies are able to kill them quickly. Definitely worth pick, though, however, Ysera's Blessing is not worth that much.

Let's start with

Aggresive Build

So, I go for aggresive build when I know that my team is pretty more tanky and when we have another support. So for example, good team composition for Aggresive build could be - Brightwing, Tassadar, Diablo, Kerrigan, Azmodan.

I pick aggresive build when I know my team can survive higher bursts + when I know enemy team has a lot of squishies, so, for example - Nova, Valla, Jaina, Li Li and Muradin.

As you will fully focus on Arcane Flare, Envenom and Emerald Wind, you will be able to 1 vs 1 any of those squishies, since combination of perfectly landed Arcane Flare, Polymorph, Envenom and Emerald Wind is just too much to take for squishy enemies. Still, you have your Soothing Mist and Pixie Dust to save you and your allies.

Aggresive build is very strong and potential, however, you have to be careful when you decide to play it, as you have to ensure your team has another support or is tanky enough, or, when your team lack damage.

Passive Build

So, for passive build, it is simple - you are the only one support in your team and you just heal your allies and support them. Enhanced Pixie Dust is extremely valuable for this build, as it creates additional Block and Spell Shield for your team mates. I would highly suggest you to take Blink Heal over Emerald Wind if you are the only support in your team, unless your team has heroes that need's to be interrupt, like Nazeebo, E.T.C., Li Li, Valla and Azmodan, then Emerald Wind comes in handy.

Blink Heal is very effective for passive build, as you can quickly jump from ally to ally and heal them, saving their lives with heal + Pixie Dust.
Your Blink Heal is supported by Soothing Mist and Gust of Healing.

Passive build is awesome for healing your allies, and enhancing them with Pixie Dust (great for tanks with Block and Spell Shield).

Utility Build

Utility build relies on shields like Protective Shield, Storm Shield and Pixie Dust.
This build is awesome, especially in one case - supporting Illidan with another supports.
So, for example, combination of Abathur, Brightwing, Rehgar, Stitches and Illidan is absolutely devastating, as you can shield and heal your allies, especially Illidan all the time. This turns Illidan in to, almost, unstoppable monster.

To ultimates, it clearly depends on you and your team composition - If your team composition would look like exactly I wrote previously, go for Emerald Wind. If you have Illidan and Abathur in your team, but no another support, pick Blink Heal, so Illidan and your allies can survive.

Picking Bribe is valid, however, pick it on maps like Sky Temple, Blackheart's Bay, Garden of Terror and Cursed Hollow, as on other maps it's a bit more useless.

Utility build almost fully relies on your team composition.

Brightwing is overall, at least for me, one of the best utility and passive supports to be in combined with.

She has powerful heals (via Soothing Mist and Blink Heal), powerful disablers ( Polymorph and Emerald Wind) and a great boosters for defense ( Pixie Dust, Protective Shield, Storm Shield).

Brightwing cannot be mostly overhealed in total healing (because of her passive that is AoE heal), but supports like Li Li and Rehgar overheal her very easily in team fights, since most players of Brightwing tend to pick Emerald Wind for utility and aggresive tools. Yet, she is very good solo healer, not like for example Tyrande, wherea's Tyrande is great utility and aggresive support.

Brightwing is great in combination with almost every support, but there are supports and even some specialists that are awesome in combination with Brightwing:

Brightwing and Li Li - Now, this is extremely powerful supporting duo. In this case, I would recommend Brightwing to go full aggresive or utility build and Li Li full healer, as she is much more stronger healer in overall then Brightwing. These two together can keep whole team together alive, even with someone going under 80% HP. Also, both of them can provide serious damage and utility things, like Li Li 's Water Dragon slow, Brightwing 's Polymorph and so. Sometimes, it is good idea to try Li Li as full aggresive support + Brightwing full passive, still worth it. Definitely GREAT DUO.

Brightwing and Malfurion - Malfurion is also very strong healer, but his Twilight Dream ultimate is extreme viable for team, because of the silence. So in this case, I would recommend for Brightwing going full passive build or half aggresive, half passive and for Malfurion mostly damage. I did not favorize this duo very much, but I believe there are some very useful tools for them combined. AVERAGE DUO.

Brightwing and Rehgar - Another great combination. Both strong healers and decent damage dealers. I would recommend Brightwing going full aggresive build, while Rehgar full healing build, as his Ancestral Healing ultimate is very, very strong. These two combined together almost never die. Just Brightwing 's Pixie Dust, Emerald Wind, Soothing Mist, Polymorph combined with Rehgar 's Ancestral Healing, Lightning Shield and Chain Heal makes these two together very deadly. Tons of healing. GREAT DUO.

Brightwing synergies extremely well with almost all other heroes, but here, I will list some of my favourite:

Brightwing, Diablo, Sylvanas, Nova, Jaina - This composition is for extreme burst. You can go easily Aggresive Build here or Half Passive, Half Aggresive, as the tactic is simple - You have your passive, Soothing Mist and Gust of Healing + Continuous Wind for longer stuns, as your allies, especially Jaina and Nova will be able to bring down your enemies extremely fast. Emerald Wind synergies also well with Diablo 's Apocalypse, so you can push up your enemies right in to it + with Sylvanas 's Wailing Arrow, as it is easier for her to land it + Nova 's Precision Strike, and, if possible, Jaina 's Ring of Frost.

Another favourite, and very strong team composition is:

Brightwing, Stitches, Illidan, Rehgar, Abathur - This composition is great for your utility build, and as you can assume, you will be supporting Illidan, together with Rehgar and Abathur. With this composition, Illidan will be almost unkillable. It depends on you and Rehgar, if you go for Blink Heal or Emerald Wind.

There's composition, that I call AoE CC - This should contain heroes with CC, like Brightwing, Uther, E.T.C., Kerrigan and Tyrande. This build is all about AoE CC, great for team fights. As E.T.C. can start with his Mosh Pit and his allies can constantly deal damage to his enemies, right after, Uther can use his Divine Storm for additional CC + Keriigan 's Impaling Blades and Tyrande 's Lunar Flare, for the final, Brightwing can deal damage and separate surviving enemies with her Emerald Wind. This combo means tons of CC and tons of damage in few seconds. I would recommend Aggresive or Half Passive / Half Aggresive build for this composition.

I hope this guide will help you guys, as I worked really hard to give you the best examples!

I'm really happy with Brightwing as such builds.

For the half build i've listen in description - it's fully up to you. I use it sometimes, combination of half utiliy and half damage is always nice, especially if you know what you are doing. So, combining talents, as I did in "half build" might be very helpful in some situations.
Ofcourse, mixing Brightwing talents in such ways is always good and if you have comments and suggestions, please, leave them below, as it might help me aswell!

Thank you!