Predecessor Builds > Sparrow > Go-To Sparrow Build
The build works well on both Sparrow and Drongo (crit rate go brrr).
flex items
Lightning Hawk and Skysplitter are your flex items. You'll want to replace them with either Tainted Rounds, or Terminus.
Dust Devil is to be replaced by Demolisher as your "5th" item, before starting Skysplitter as you "6th" item.
Replacements
Tainted Rounds and Terminus are your best items to swap in. An argument could be made for Viper, but it's a tad redundant when paired with Demolisher
Build Path Reasoning
You could go Vanq for your first item, get that early pressure from its execute passive. But you don't get any attack speed from it, which I find preferable.
It's the same reason we don't build Demolisher or Imperator first; no attack speed.
"So why not build Tainted Rounds first then?"
Tainted Rounds is a really solid item against healers, and anyone specing into healing (Raiment of Renewal, Lifebinder, etc.). However it has less power than Lightning Hawk, which in my experience has made a huge difference in the early game.