Predecessor Builds > Kwang > Kwang Support (Core 4 Items)
When you can land tethers, Kwang has the potential to be a strong support. He has great ranged poke and a great gap-closing knock-up. I have been running him in support recently and finding success more as Kwang support, as opposed to Jungle or Offlane.
Of the builds provided, damage tank seems to be the most viable. That is, with all of the damage tank items, Fire Blossom, Fist, Elafrost, World Breaker and with items like Stonewall and Tainted Bastion.
Skylar's recent release has made me want to experiment with Hexbound (Kinda a shit item), but its passive negates about 25 flat damage at level 18 of a Skylar RMB, which is about 25% of the damage from each instance.
Obviously if the opposing team is entirely magic damage, ditch Stonewall for Bastion, Cuirass and/or Unbroken.
The Let Me Cook section is for items that give Physical Power (not desired on Kwang), but have passives that could be of benefit.
Lunaria is (kind of) a meme. Kwang loves to box with people in lane, so if you picked up Lunaria and Tranquility, you could heal your ADC in lane in some decent chunks. I would have to try it extensively to see if it actually works.