Lux can be deceptively durable using Prismatic Barrier; use it in teamfights to grant yourself and your entire team a strong absorption shield.
On cast, Prismatic Barrier will instantly cast the shield on you, and when the rod returns it resets the shield on yourself. When running, cast Prismatic Barrier in the direction you are running. This way, you will be shielded twice, faster.
Lucent Singularity provides sight. Use it to check bushes or gank spots before approaching to prevent an unnecessary death.
A useful trick is to cast Lucent Singularity, then auto attack; while your auto attack is in the air, detonate the spell so you can get the Illumination passive to detonate right after. If you detonate right after casting however, you may not have the vision to execute the attack.
Using Final Spark to hit enemies who are attempting to Dragon or Baron Nashor may allow you to scare them or even kill steal the Dragon or the Baron buff. Similarly, it can be used to finish off the monster when your team is attempting the kill.
If Lux is used on the map Twisted Treeline, her ability Final Spark from the middle brush can target enemies at the tower. This gives Lux and her team an advantage in lane control.
It is advised for Lux not to get into a close-up fight, as her low movement speed, long cooldowns, and relative fragility will work against her. Stay behind your teammates and spam spells into fights from afar to stay out of harm's way.
Having a strong map control or Clairvoyance is an effective way to see enemies in the fog of war, allowing for well-placed/timed Final Spark on low health enemies or epic monsters.
Final Spark is great for clearing large amounts of creeps in a lane, and harassment in late-game due to its noticeably short cooldown.
Feel free to use Final Spark just to shave off some of your opponents' HP, due to its low cooldown and high damage output.
At 40% cooldown reduction Lux can perform it every 30 seconds, which is low enough that she can use it to soften up enemies in a teamfight and then finish off any escaping opponent.
During the laning phase and depending on the situation, you can use Final Spark before recalling to stop a push or scare off the enemy as the cooldown, even at early ranks, is not very high.
However, one of Lux's most effective combos is a Light Binding followed immediately by Final Spark to proc the passive and deal unavoidable damage to those caught. This can effectively turn a fight around if you manage to catch priority targets with this.
The damage of her ultimate Final Spark extends slightly past the targeting icon, but enemies will likely dodge it if they are at the very edge.
Lux can easily punish enemies who overextend or chase her down by kiting with Lucent Singularity, especially in the jungle, and will make it easy for you to use a Light Binding and Final Spark combo right after for damage which will either scare them off, finish them, or weaken them enough for your teammates to finish the job.
It is strongly suggested to use smart cast as Lux requires fast initiation of spells to pull of her whole combo.
Do not neglect her passive Illumination at any level. Lux does not put out the most reliable damage, but has a high per level scaling on her passive. In comparison, if you were to fire off a Final Spark at level 11 with a Rabadon's Deathcap, the bonus damage on your ultimate and the bonus damage from your passive would be roughly the same. Spacing your abilities apart and weaving in auto-attacks between each of your damaging abilities will drastically increase your damage at all levels.
While not played as often, Lux can be played and built to that of a support, requiring a more passive approach to curb her mana costs and lack of hard and reliable disables.
When ulting escaping enemies, minimize angle of enemy vector and ult path. Sidestepping in a lane helps.
Lux is a burst mage with a fair amount of team utility but long cooldowns. Thus she benefits most from ability power, cooldown reduction, and mana regen.
Ability power simply improves the strength of all of Lux's abilities. The primary item of choice for this is Rabadon's Deathcap.
Void Staff is an important item while getting to the later phases of the game. Many enemies naturally gain magic resist as they level, and after a certain point they are able to brush off Lux's attacks. Penetration helps to make her spells hit harder and be more effective in fights.
Twin Shadows can also be a decent item on Lux, giving her not only AP and CDR, but a little movement speed as well. The active in particular will make it much easier to land her Light Binding or escape from pursuing enemies.
An Elixir of Brilliance is a decent way to cap out your cooldown reduction, while also granting a fair amount for ability power for 3 minutes.
It is worth mentioning that getting an Elixir of Brilliance is not always a good idea. Rapidly getting it puts your gold income into a slope and delays more important purchases
A Lich Bane on Lux can be effective in adding another source of damage to a kit that already encourages auto-attacking. However, players should always be careful about getting too close.
Prismatic Barrier does not do any damage, thus you do not need to dodge it. However, be ready to dodge Lux's other skills.
Due to the small and narrow paths in the jungle, Lux's spells become more than likely to land, enabling her to fully use her combo, which can devastate any carries or squishies.
This also becomes a problem / advantage in team fights that occur in these areas. Lux can easily deal massive damage to enemies who stand in a line.
Lux'sPrismatic Barrier is also more than likely to hit, shielding all her allies which will cause a large problem / advantage, preventing a large amount of DPS dealt to her team.
Lux is generally countered by champions that can survive her burst and chase her/close the distance, such as Wukong.
Lux is a skill shot based champion. Though her abilities move rather quickly, it is still possible to dodge them. However, Final Spark fires instantly; using Flash to escape being hit by this may be necessary.