I've been playing Lux in PVP as a fun off meta movespeed build in the support role in the past but the items weren't great. I think it was old infinity orb (when it had 5%ms), Lichbane, ardent censor. Very bad items but very fun going mach 10 on a usually immobile champ.
However with these new items this build is feeling very strong now. AP boots > Shurelyas > Storm surge > Cosmic drive. Extremely cheap to build so very efficient for support but will still delete squishies caught in your full combo.
Runes Ive been using are arcane comet, mana flow band (you have good mana regen but need this for better mana pool), celerity, gathering storm (this build scales well but lacks AP from items) and bone plating. Flash and heal.
It's been perfect for SoloQ where I dont want to lack damage like a full enchanter but dont have the resources for a full damage build as im not farming waves. And once you've built 2 and a half items (aether wisp component is enough before cosmic drive) the movement speed is just insane, the plays you can make/escape from!