haha no problem! I reread through your guide and I noticed some things, so I'll point them out here.

1. I would take Jinx support out. This actually goes with all of what i am going to write, but I am not sure how low elo works honestly. I have always been gold or above. But I do know that Jinx support would never work unless the Jinx is really good or your team is bad haha

2. I would honestly put Janna on a harder scale. She is able to heal and shield very effectively, and a good janna will have some meat on her with tons of CDR to block your poke constantly. She is a high tier support.

3. I would put in the suggestions on going vs say a Janna or an Alistar to take Ignite! If you are engaging and you catch Janna with your light binding, you will want to ignite her, as it stops her heal.

4. I play Lux supp for fun every once in a while so I'm not too sure, but is Meditation really better than merciless? Lux does have early mana issues, for sure, but I think the damage under 40% might be better, especially with Lux's ultimate and damage she is able to give out. Not to mention, Meditation won't be used much later in on the game- but that extra damage from Merciless will throughout the entire game. However, if you have tested it out and meditation REALLY helps that effectively, I would keep it.

5. I'm really not sure about the idea of taking the resolve mastery side for Lux. Insight and Explorer could be proven useful, but Lux's job as a support is to peel, give damage, and shield. I would take the resolve side if youre going a bit tanky and are buying items such as Zeke's Harbinger, Locket of the Iron Solari, Mikael's Blessing, Ardent Censer, etc that helps your adc out (same idea as some of those who go a tanky morgana) but I don;t think that is your idea of this guide, as Lux really IS obnoxious! However, I would still recommend taking ferocity due to the Expose Weakness for your adc and Sorcery/ Natural Talent / Oppressor to further your damage (and poke!)

6. I think you should have items such as Luden's Tempest as situational. As a Lux player, I don't buy the same items EVERY game. Luden's is perfect if you need the movement speed for enemies like Brand, Xin Zhao, etc. It's more of a utility than anything, plus it gives a whopping 100AP. Luden's is a really good item so I wouldn't just scratch it out. Also adding other items, like Banshee's Veil, would be a great situational item.

7. Abyssal Mask is another one I would add as a situational item. It's passive won't be used all the time, but the AP+MR+CDR is pretty strong actually. I also would add Zhonya's Hourglass if needed. Every game is different and you never know what to expect.

8. Maybe it works in lower tiers, but Lich Bane is a big nono. Either you won't be proc'ing the passive anyways, or you will go in too close to auto, which could cost you your life. Remember that your ultimate proc's your passive!

9. Banner of Command is actually a hella good item! It is 'supporty' as it gives MR to your team, but also provides AP- which we both know Lux needs. Not to mention, that big minion helps pushing and seiging on turrets and such.

10. This is personal preference, but I hate Guardian Angel honestly on Lux. Lux is so squishy and vulnerable that it really won't help much and I think other items like Banshee's Veil and Zhonya's Hourglass provide more. However, this is personal preference and it does serve a purpose. You could put it under a situational content.

11. I would add Mercury's Treads! The tenacity could save your life- especially if you get a big Enchanted Crystal Arrow from Ashe to the face!

12. Personal, but I would add Jinx as another really good ADC. Some may say that Jinx needs hard tank and peel because shes so vulnerable, I think otherwise. A good Jinx will know how to position, not to mention, Lux's Light Binding +Jinx's Flame Chompers! means they aren't moving. And they can both snipe the enemy with their ultimates!

13. I would suggest explaining your ability sequence. I catch myself having to get Prismatic Barrier at level 3 instead of 4 whenever I am against a pokey lane (ex: Caitlyn+ Karma. The shield will really help both you and your teammate soak up some damage, and even win trades.

That's all I wrote down, but I am sure you can add and edit much more. Good luck with everything, I hope I helped at least a little <3
(remember that everything I said is just my personal opinion and let me know if you think I am wrong, as I will take anything into consideration. Learning is my favorite thing so. Take what I said as a grain of salt and do what you think is best)
happy lasering!
-LuxTheGreyWarden

Take it from me that being able to have free wards on the map is worth much more than that 200-300g bonus income you get from Frostfang. If you prevent ONE single gank (not to speak of doublekills or repeat ganks if you lose flash), the sightstone purchase is already worth more. That's not to speak of the extra safety you get from the bonus health as well.

Frostfang first isn't bad per sé, but it is much more risky because you're left vulnerable to two things: all-ins (lack of health) and ganks (lack of wards). Sightstone typically outearns Frostfang by a sizeable margin because it denies the enemy gold that way. The times I do get Frostfang first, I do so because I have a favourable matchup and want to destroy them as hard as possible through the extra AP and mana regen you get from the item. It remains a greedy thing to do and not to be recommended to inexperienced players.

Also, correct me if I'm wrong but your maths assume that you make optimal use of the tribute passive (proc when off cooldown). Unless you're playing against really poor players, you generally won't be able to get these procs off all the time because you have to be somewhat smart about trading hits.

(edited) Also, a bit of side information: for my general build path for all AP-ish supports like Karma/ Nami/ Sona I tend to delay or skip Frostfang until I've finished Sightstone + Tier 2 boots beacuse if utilized correctly, the utility you get from these two is worth more than some small amount of extra gold generation can offer you. Mobility and vision are two massive enabling elements for your team and can win you the game early on.