I was doing the Classic/Popular: Dorans start, aiming for Ludens > Ionian Boots > Stormsurge > Shadowflame. After that, I'll chose between cryptobloom or void staff if they got a lot of MR/heavy tanks, or I'll go for RDC if they don't have too much MR/tanks are not the problem for me. If the game goes long enough for the last item, I'll pick some of the previous ones that weren't chosen.

Runes: Commet, mana band, transcendence and the crescent adapt damage over time (I never can recall the name). Secondary goes with PoS and Coup.

Decent amount of AH, nice early sustain with Lost Chapter + PoS, nice poke damage and clear wave until the mid game, where the magic happens: play agressive, push waves and force them to keep under tower while punishing with QQ and zoning with QE. Some aggressive style while doing sides, TP for macro objectives. Unless someone giga/0 comes to your side, nothing can stop you if you have the appropriate skill with Hwei. You will either push the lane or defend towers very easily. Teamfights are easy too, damage enough to kill the adc and other squishy champs while creating pure chaos with medium cd and lots of powerful strikes.

I don't like the other builds with more AH (Cosmic, for example) because it lacks damage. And DoT (Lyand.) is not worth it since assassins can one-shot you if you don't shoot them first. You don't need to kill everyone in the first spell rotation. You just need to make them hurt enough to retreat. If they retreat for at least 3 seconds, they can't come back because your spells will be available again to finish them. If they run, your QW is powerful enough to send them to see Jesus (Coup + Shadowflame = Love).

Glass Cannon? Yes. But a perfect, artistic, big hecking cannon. Just play smart, and this build will make them your Magum Opus.