Build Guide by Arinrinrin
Not Updated For Current Season
This guide has not yet been updated for the current season. Please keep this in mind while reading. You can see the most recently updated guides on the browse guides page.
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Before We Start
There are some things to be noted with this build. For starters, you may have noticed that I only put 2 items in the Item Sequence. This is because I have decided to only list Lux' ideal starting items. Since Lux doesn't spam her abilities frequently, partly because of her high cooldowns, she takes a while before she get the 1000 extra mana from Archangel's Staff. It is therefore crucial to get the Tear of the Goddess since that will help her immensely midgame which is the primary point where she struggles with mana. Afterwards, I like to go for Catalyst the Protector. Catalyst of the Protector has great synergy with Tear of the Goddess because it allows you to stay longer in the lane, which lets you cast more spells. It makes sure that Lux doesn't have to rely so much on recalling to base all the time because she is low on health or mana. Afterwards, it is a good idea to get Rod of Ages because you will want to be 'charged up' for when you start midgame, where you will need the extra health. At this point, you can choose whether to go for some boots first, and then go Archangel's Staff, or go straight for Archangel's Staff.
Boots: Or How I Debated What Pair To Wear Today
The choice of boots that you buy for each match should always be dependent on the team composition. As of the 3rd of January, there are only two good pairs of boots for Lux to buy, however tomorrow, the 4th of January, there will be a new pair of boots, and after testing said boots with Lux, I will change the build to include those.
Mercury's Treads is almost always a good choice for Lux. She has no real escape abilities, but only abilities to make sure that the enemy never gets too close to her. Mercury's Treads will help you out if you are the most threatening squishy on the team, since that means that in team fights, the enemy team will attempt to stun/snare/slow you to oblivion while smashing you to pieces. HOWEVER, Mercury's Treads should /only/ be bought if the two following conditions are met:
You have no tank
You are the most threatening squishie on your team.
Being the most threatening squishie on your team means that you do not have a caster or ranged phys dps that are known for high burst damage or extremely high consistent damage. This includes, but is not limited to, Karthus, Ryze, Annie and Ashe. If in your team, you have someone like this, you can instead use Sorcerer's Shoes, because that means that 90% of the team, the enemy team will go to EXTREME lengths trying to kill them, ignoring you in the process.
The Core Items: Or Why You Should Do As I Say
The core items on Lux will change depending on what position in your team you desire to be. Are you lacking an off-carry on your team? Or are you asked to be the primary support character of the team? And the core will also depend how confident you are with using Lux. The only item I'd say that you should /always/ get is Archangel's Staff, since it will help Lux with her mana problems, as well as giving her a lot AP.
To clear things up, Lux is /not/ a carry character at all. She is a support character with a very high damage output if built right. However, if your carries are /not/ doing their job sufficiently, or you are lacking a carry, then Lux can help out in this regard. However, she can not do something which is crucial for a true carry; being able to push towers fast. Therefore, it is to be noted that if you are built as an off-carry, that you will be only be good for taking down champs and creeps.
If you are new to playing as Lux, then start with the item sequence that I shown above, followed by the correct pair of boots, (read Boots: Or How I Debated What Pair To Wear Today). After this, you will need to look at the team composition. As an off-carry, you can only afford one defensive item, so you need to see which will benefit you more. Are the majority of the enemy team magic damage dealers? Pick up a Banshee's Veil, or even a Hexdrinker if you are having /a lot/ of trouble with characters like Karthus, Ezreal, or even an enemy Lux. However, you must note that Hexdrinker does NOT scale well with the game. Once you feel that Hexdrinker has become useless, buy a Banshee's Veil instead. If the enemy team has a lot of physical damage dealers, then buy a Frozen Heart, (the CDR will help A LOT), if it's Attack Speed champions, like Yi, or a Thornmail if you're against Attack Damage champions, like Ashe. I would like to note though that the advantage of Thornmail over Frozen Heart is minimal, and that Frozen Heart should almost always be the primary choice. If the enemy team is mixed, then a Frozen Heart and a Rod of Ages is usually better.
Assuming you got both the Frozen Heart and Rod of Ages, you now have four spots occupied, (Archangel's Staff, Boots, Frozen Heart and Rod of Ages). If the enemy team have a particularly high-health tank, then getting a Deathfire Grasp is very good, even if it'll put you over the CDR threshold. If they don't, then an Abyssal Scepter is a better choice because of the aura. Round it off with a Zhonya's Ring for the delicious amounts of AP, Unique Passive and Unique Active.
If you say that you are very confident with using Lux, and you want to be the off-carry of the team, then Rod of Ages should be your only defensive item. Lux' spells have one of the highest average range per spell in the entire game, allowing her to stay far in the back without worrying about getting hit during end game team fights. Usually when I am playing against an enemy Lux, they usually die because they decide to walk too close to the action, which will get them killed instantly. As an experienced Off-carry Lux, you need to make sure that you do not get baited by the enemy team. Usually, a good indicator of the enemy team attempting to bait you is found by simply looking at the minimap. Are more than 3 enemy champions dead? If no, can you see 3 or more enemy champions on the minimap? If no, are you alone? If yes, then it's not worth the risk.
After getting Archangel's Staff and Rod of Ages, you will want to get as much AP as possible, while also hitting the CDR cap. With runes and mastery, you should have approximately 10% Cooldown reduction. Deathfire Grasp, while a very good item for other casters, is not optimal for a Lux with no defensive items because of its EXTREMELY short range. It is therefore better to get Nashor's Tooth as it allows you to autoattack the enemy while waiting for your cooldowns to finish. Alternatively, you can skip Nashor's Tooth altogether, and instead just get the Golem buff whenever you can. It gives roughly the same amount of cooldown reduction, while giving mana as well. The only downside is that if you can't get to the golem, or someone else takes the golem buff repeatedly, then you are screwed since you won't have sufficient amounts of cooldown reduction to play correctly.
So, if counting Nashor's Tooth, you now have 4 item slots occupied. To augment Nashor's Tooth, it is always a fine idea getting a Lich Bane, since it will increase your average damage dramatically, especially since you will /have/ to autoattack your target after every spell since you want Illumination to proc. Top it all off with Zhonya's Ring, and you're good to go as the off-carry of the team.
TO BE ADDED: Support Lux: Or How I Learned To Stop Killing Things And Love The Support In Me.