In most of the Lux is UP post one of the more common complaints I see is that Lux has bad AP scaling. So I though I would run some numbers. Keep in mind that this does not take into account DOT, AOE, cooldowns and if its a shield, heal or damage. Its just how much extra does the champ get from 1 AP.

[Zilean ] [ .9 0 0 3.0 ] [3.9]
[Soraka ] [ .25 1.0 .6 1.3 ] [3.15]
[Morg ] [ .9 .2 .8 .9 ] [2.8]
[Janna ] [ .75 .8 .9 .175 ] [2.625]
[Vigar ] [ .6 1.0 0 1.0 ] [2.6]
[Swain ] [ .9 .7 .8 .2 ] [2.6]
[Tric ] [ .9 .5 1.0 .2 ] [2.6]
[Lux ] [ .7 .3 .6 .75 ] [2.35]
[Ezreal ] [ 0 .7 .75 .8 ] [2.25]
[Anni ] [ .6 .6 .2 .7 ] [2.1]
[Kennen ] [ .66 .45 .55 .33 ] [1.99]
[Sona ] [ .6 .5 0 .7 ] [1.8]
[Anivia ] [ 1.0 0 .5 0.25 ] [1.75]
[Kayle ] [ .8 .5 .3 0 ] [1.6]
[Karthus ] [ .6 0 .25 .7 ] [1.55]
[Ryze ] [ .45 .2 .38 0 ] [1.03]

These are some of the other casters and support champs seems like she is just middle of the road to me.

Pretty sure her passive ignite is also party of her ability to do some nasty damage.

Anivia has two 1:1, and a potentially infinite ratio on her R.

Your forgetting that all of luxes abilitys are ap.

Some of other champs like say ezreal have ad scaling skills, or skills that dont scale and just have an on hit effect (vigar), or have skills that hit many many times like swains ult or morganas pool.

All of luxes abilities are ap scaling and dont have that multiplied by ticks, she is mid table but should be further up.

This also does not take into account the base damage of a skill, or its intended use.

The only character she can really be compared to in your way is morgana, who you show destroys her in terms of ratios.

To be honest, keep the others the same, but give back her old AP ratio with her ult (0.9) and I'll be happy.

Either that, or give her passive CDR back with W. Failing all else, passive igniting also on spell hit would go a long way, if Shurelia's idea would go through.

Still, without any buffs, its not as if she's unplayable like Swain was and Urgot still is.