Lux can be deceptively durable using Prismatic Barrier. This allows her to stay alive in team fights much longer than expected.
Use Prismatic Barrier in teamfights, granting 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.
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 kill 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.
Lux can easily punish enemies who overextend or chase her down by kiting as it's easy to have them go through your Lucent Singularity especially in the jungle, will make it easy for you to use Light Binding and your Final Spark right after for damage which will either scare them off, finish them, or burst down their hp enough for your team to finish them.
Lux has prime lane control, making a Catalyst the Protector very useful to ensure dominance giving Lux enough health and mana. This can later be built into a Rod of Ages, granting a fair amount of Ability Power while giving Lux a good health pool should she be focused. The mana granted is also useful to stay in fights longer.
As Lux can stay relatively far away from a teamfight, AP should take priority over survivability. Rabadon's Deathcap is the most efficient way of doing this, making all her spells much more potent.
Since Lux's abilities have long cooldowns, cooldown reduction is crucial to her utility/damage.
Since Lux'sFinal Spark, has a relatively low cooldown and long range, it is best to stack up on AP and cooldown reduction to make it more potent and effective in weakening enemy champions before or during a team fight. Final Spark can also finish off enemy champions on low health that are retreating.
Building Archangel's Staff will grant Lux a fair amount of mana and ability power, allowing her to spam her abilities.
Since Lux generally stays behind her team in team fights and she can survive random chases due to her crowd control abilities, you can get Mejai's Soulstealer and manage to keep your stacks high, giving you a fairly high amount of AP and an edge over the opposing team.
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 moves quickly; using flash to escape being hit by this may be necessary.