Is it just me or is lux's W weaker when building support?

That's how it should be... She's a mage first, support secondary, and her AP ratios reflect that.

Lux, on a whole, scales very well with AP - that's why typically Morgana is preferred as a support, since Morgana's base stats are already nice so she isn't quite as reliant on AP in comparison to Lux. Lux's base stats aren't really all that great, but her AP ratios on most of her skills are much better than the after-mentioned Morgana.

This is Lux's shield stats: SHIELD STRENGTH: 50 / 65 / 80 / 95 / 110 (+ 20% AP)*

In comparison, here is Lulu's shield stats: SHIELD STRENGTH: 80 / 120 / 160 / 200 / 240 (+ 60% AP) And here is Karma's (non-empowered) shield: SHIELD: 70 / 100 / 130 / 160 / 190 (+ 50% AP) Janna: SHIELD STRENGTH: 80 / 120 / 160 / 200 / 240 (+ 70% AP)

Lulu/Karma/Janna on average are going to have less ap in their builds, so they're able to scale with more AP to make up for it. Lux, however, has weaker base shield stats, it's potentially team-encompassing but otherwise not reliable (being a skillshot whereas Lulu/Karma/Janna are point and clicks), and there is a delay before she gets the 'full' benefit (eg the shield-boomerang effect). While the 20% AP scaling looks lame Lux is going to have a lot more AP than Lulu/Karma/Janna so she still ultimately gets more out of it... But if Lux doesn't have AP, the shielding boosts on items like Mikaels, Ardent, etc. only work so well for her.

tl;dr Lux is first and foremost a burst mage and is likely to build a lot of AP. She has weak base scalings with her shield in order to balance her kit, so an AP Lux is going to get more out of AP than a Utility Lux will get out of shield boosts.

*This is the initial cast. When it comes back, this is doubled to a total of TOTAL SHIELD STRENGTH: 100 / 130 / 160 / 190 / 220 (+ 40% AP)

As for more tl;dr math I know someone on the /r/karmamains figured out the math for Karma specifically (so take this as a grain of salt) had it so 40 ap = the same benefit as a single shield-enhancing item. I'm not good at math, to be quite blunt, but I imagine the AP ratio = shield boon is going to be a lot less beneficial for Lux, since Lux has a weaker shield to begin with. It's not that she can't go for a utility build but she simply gets less out of the items.

Don't take windspeakers on lux. The auto passive damage with thunderlords is too good to pass up even in support.

Money is a hell of a thing.

Wait.... windspeakers support lux?

You are still the carry. Run TL like a man!

Originally had a large comment with the math behind this question, but chrome shut down and deleted it.

Tl:dw(too long didn't write) As long as you can get over 550 ap, a Lux building ap will do better shield wise than a Lux building and windspeakers. However, if the Lux builds instead of it takes 760 ap to outdo her.

So ap Lux is superior, if you can get the 12100+ gold required for the 760 ap.