TL;DR
I like to type I suppose. So here's the summary: You are a commando. Run around and destroy enemy structures. Take out groups of minions to assist your damage output and otherwise soak.

I honestly think Sylvanas builds are pretty subtle in their differences. So long as you don't choose any of the really bad skills you should be good.

My play style leaves me to pushing a lot (since I was confused in the past and "thought I was an assassin"). I clear lanes and destroy towers and forts...And I'm sneaky about it probably as much as Nova players love sniping off weakened heroes. I love it and my siege score is off the hook. For those of you who like seeing a big score on the scoreboard (that does mean something for winning).

This build is a modification of many that you'll see here. Please read Jaeris' complete guide on Sylvanas here as those are wonderful builds.

So why did I deviate from them? Well, it all came about when I realized Withering Fire wasn't as strong as the basic auto attack (30; +7 per level for auto attack (1.67/s rate of fire) vs. 25; +3 per level for withering fire. At level 20 that's 170 vs. 115). Nor is the range any better even with With the Wind you're limited due to Cold Embrace. So since it does less damage and there's only 5...I decided not to manually use them! Sure you can spam 5 out faster than your normal rate of fire, but I figured out something better (later on).

Early in the game I'll still use Withering Fire because there's no bonus yet...But once I get Overflowing Quiver that starts to slowly change. It's over and my manual use of Withering Fire is done once I get Unstable Poison.

Why? The rationale here is that Overflowing Quiver fires off free Withering Fire on each minion and hero kill. You know how you can clear like crazy with Unstable Poison? Yea. Tons of free withering fire.

So you just work it like you normally would. Most people say only use Haunting Wave to escape...I agree, but if you have good situational awareness, I've used it to help clear minions. It's quite nice and reminds me of Raynor's penetrating round only without knockback.

As you start picking off minions, free withering fire arrows start flying. It helps you sustain good damage output. Think about it. 5 charges you can fire off or a wave of 10+ minions? You simply fire more withering fire arrows this way.

Have you ever had unstable poison stop short? Where it just didn't have enough power to get them all? That clears up with this approach and you can clear lanes more effectively sooner.

Aside from clearing lanes, Sylvana's strength comes from stunning towers. You can solo the enemy forts and towers...And you should. There's no reason not to and I love running from unprotected structure to unprotected structure.

Note that you should probably change locations after taking out a structure. The enemy team will be alerted and if they are smart, they'll run over there fast. However, I've found (in quick match) many people ignore it and I've taken out sometimes two structures before I found enemies upon me. Once I cleared two towers and a fort in one sitting.

Remember, Unstable Poison is very sneaky. It explodes minions and as you sit next to their fort and tower, you should be putting constant auto fire on the structures but then use Shadow Dagger on the minions. This is where I also use Haunting Wave to help take out the minions while not breaking fire (at least not for too long) on the structures. It is sometimes the only way to get those minions off your back. Since you don't want to use Withering Fire in fact, as those minions begin to die, your withering fire is hitting the structures around you! I get right up on top of the structures so they are the closest target most of the time. If your free withering fire hits a minion, meh so what...Take another one if it dies.

Point is: You can actually take out minions while you're sitting there taking out structures. However, IF you fired your withering fire charges, you wouldn't have as much sustained damage output and it would be harder to do both.

Minions splode on structure? Excellent, structure go down faster.

As for higher levels... Splinter Shot can be swapped for whatever you like - but if you want to push, I'd keep it if you're pushing. That's a lot of free damage once you get on a roll. Since you are trying to not manually use withering fire you can't rely on Evasive Fire but it can help you get out of a jam of course - but I think a jam you shouldn't be in. Your play style should be hit and run. Overwhelming Affliction is also nice. Again, you could use any of these, but splinter shot will help you push the best.

Then Cold Embrace is a no-brainer. This is my least favorite tier, but I doubt they could ever redo the skills and provide something that would make it a tough call over cold embrace.

Last, Fury of the Storm is the ultimate finish to your push build here. Bolt of the Storm is acceptable if you're still looking to escape. I actually would take it more except that by the time level 20 rolls around, most their towers and forts are toast.

I did not list any threats in this guide because every hero is a threat. Avoid them all. Go to the next unprotected structure or lane. You'll be more effective there than messing around with enemy heroes.

Look, taking out towers and forts and gates... That's a team player right there. You will get people annoyed that you aren't helping with objectives and such. So feel free to do that as you feel fit. Sylvanas can take out siege camps quite nicely and maps like the Haunted Mines, she can clear super fast mid-game.

The problem is - you're squishy. If you get caught, you likely will die. Timing haunting wave is very difficult and people can stun you. So it's really a bonus for me. I never rely on it, but smile when it saves my butt. So I never fight heroes these days (solo or for anything more than a quick assist)...But you can help out a team.

It's nice if your teammates help you take down structures, but I actually see Sylvanas as more of a lone wolf. I think it's better if they distract the enemy heroes to be honest...Because you really want those enemy heroes far away from you. Again, situational awareness. You may see enemy heroes coming back from attacking...Yea...You know where they are going. Head the opposite direction and attack a different structure.

Remember, you can pull enemies off their push by taking out structures. It alerts them and they start to get nervous. That's also being a team player. You don't need to take out enemy heroes to pull them off your base.

If you aren't destroying structures...If you want to defend - you can and should. Stay safe, but use cold embrace on heroes. It'll help your team out tremendously.

Look for enemy heroes surrounded by enemy minions. Get your unstable poison on those minions and they will explode all over the enemy heroes. They really don't expect it. Not many people think to stand away from their minions. They think, "oh, a buffer, they'll help protect me and people will click them instead, etc." Does not apply with Sylvanas.

So you can certainly be a team player and help with heroes, but I think the biggest benefit is clearing lanes, destroying structures, and taking out enemy minions that happen to get too close to your core.

If I'm going off on a structure raid and see a wave of enemy minions, I stop to take them out. By the time I finish getting to my destination, my shadow dagger has recharged. This is part of why Lost Soul is important - shadow dagger is your main damage dealing skill because Withering Fire is not. I honestly think it's a trap (unless you're choosing skills specifically for it - which is basically only evasive fire since you'll likely choose lost soul for your first talent). I say, ignore using withering fire manually (I know, spamming the Q key feels like you're doing something good, but you aren't) and keep it as a passive free damage bonus. Thoughts? I'd love to see some comments below.

You may not want to play this build on Cursed Hollow because if your team can effectively curse the other team, minions have no health and structures aren't a real concern. On that map, I'd play Sylvanas quite differently. Though if your team is not getting the curse, then it wouldn't be too bad to keep pushing.

You may also not want to play this build if you have a bunch of support on your team. If you don't have many strong characters, then you might want to consider a sustainable Sylvanas builds (unless you have enough healers) and look to help weaken enemy heroes with Cold Embrace. You also likely will choose Envenom at this rate too.