Predecessor Builds > Sparrow > Sparrow go brrrr (updated v18.3)
With the item rework, Sparrow seems...kinda busted. The key to this build is that in the past, Sparrow players had to choose between maxing attack speed and building to 100% crit-- the 6th item slot/increased gold income/the new plasma blade item mean that you no longer need to choose, because you can get both!
Sparrow background info, for those that are new to the character: your basic is king, and your goal is to concentrate on single targets to build your passive relentless stacks. This is why leveling your E is your number one priority--you up your attack speed, which gets you to max stacks faster and gives you the DPS needed to shred tanks for your team. Q is taken first not to push the wave, but to use as a slow in case of early ganks/hard pushes by the opposing duo. You absolutely need to keep the creeps on your side of the river, because until you are truly online (around 3-4 items, in a normal, even game) you are both an easy and very high priority target for the other team; if you push the lane constantly, you will get less farm in the long run unless you are able to secure multiple early kills on the opposing duo. This build will help you be able to do that, but a nice and safe laning phase is the goal.
Stormbreaker first--40 physical power and 35 attack speed is more than any other single item, and we want to start stacking the lightning effect from it as early as possible. Surviving in lane until 2650 gold (to finish the item) is a huge power spike, if you can pull it off.
Like before, Sky Splitter is next for the decent boost to attack speed/physical power, plus the extra bit of sustain from its lifesteal. It's still a strong item, and it scales very well the whole match.
We pick Lightning Hawk next because, again, it has relevant stats and a useful ability at this stage of the game, and it allows to start building towards 100% crit chance. Lightning Hawk and Stormbreaker's effects are generated the same way ("momentum"), and in the long run the added damage/slow effect offers your team huge utility, as mid-game exchanges are often decided by how many players from either team can escape--your slow might secure that one extra kill that leads to a snowballing win, or break momentum the enemy team has gained.
The final three items here can be flexed in terms of order, but are all strong enough to have a very secure spot. The key with the item selection here is that all three of these help us max our crit chance, now that we're close to maxing attack speed already.
Tainted Rounds gives us the extra bit of attack speed we still need to hit the cap (while our E is active). Bruisers seem quite strong this patch, and in particular if the opposing team has a fed Grux/Khai/Crunch/etc (high sustain bruisers), you will probably want this 4th. If they're extremely fed, consider even buying this 3rd!
Your fifth item should usually be Plasma Blade--this is THE KEY to why you can now reach max attack speed and max crit chance. As Sparrow, you attack so fast that getting to 5 stacks of this is extremely easy, so it might as well read 25 physical power/35 attack speed/40 crit chance; every carry would pick this item in every build if that's what it said.
Finally, finish with Demolisher. By the time we're buying this, the max health difference between us and the opposing tanks/bruisers is at its peak, so you maximize the power spike from this at the end. Notable also is that it gives us the last 20% crit chance we needed to hit 100%! 20 from LH, 20 from TR, 40 from PB, 20 from Demo means your attacks do 1.5x damage EVERY SINGLE SHOT.
If you have a game go past full build (35-ish minutes) and the enemy team doesn't do a huge amount of healing/has really big tanks, consider swapping tainted for dust devil--similar raw stats, plus a more useful effect vs a huge tank or objective (shred them even faster).
Using a calculator to simulate DPS, this was the highest I could come up with. At level 18, without swapping tainted out, first shot is doing 1012+314=1326 damage plus a 30% slow (assuming a crit); with everything proc'ing and all abilities active, you deal 1382 phys + 332 magic + 146 true = 1860 damage per, 2.77 times per second = 5152.2 DPS. This is in an ideal world, but expect (with occasional misses, armor resistances, etc) somewhere in the neighborhood of 3500DPS; with very minimal help (someone to tank), you can probably take prime/fang in less than 15 seconds as the only source of damage.
