Xayah
Threading the Needle
Lane harassment and consistent damage output.
Precision
Improved attacks and sustained damage
Lethal TempoAttacking an enemy champion grants you Attack Speed, up to 6 stacks. At max stacks, deal
bonus adaptive damage On-Attack.
Absorb LifeKilling a target heals you.
Legend: BloodlineTakedowns on enemies grant permanent Life Steal, up to a cap. Once the cap is reached, increase your max health. Weaker earlier but stronger later game than other Legend Runes.
Coup de GraceDeal more damage to low health enemy champions.
Sorcery
Empowered abilities and resource manipulation
Manaflow BandHitting an enemy champion with an ability permanently increases your maximum mana by 25, up to 250 mana.
After reaching 250 bonus mana, restore 1% of your missing mana every 5 seconds.
Gathering StormGain increasing amounts of AD or AP,
adaptive over the course of the game.
Adaptive Force
+9
Adaptive Force Adaptive Force
+9
Adaptive Force 
Health Scaling
+10-180 Health (based on level)
Why Lethal Tempo
Lethal Tempo's additional Attack Speed is massive for empowering you to get your feathers out quickly and get as many auto-attacks off as possible during your [W].
Why Absorb Life
Overheal paired with Fleet Footwork is great for absorbing and sustaining lane poke from mage supports. The extra health shield keeps you ready for a fight at any moment.
Why Legend: Bloodline
Bloodline's bonus lifesteal pairs well with the rapid attack speed from Lethal Tempo and Overheal to keep you topped off in lane.
Why Coup de Grace
Coup De Grace is an all-around reliable source of damage when looking trying to kill squishy targets with [E].
WhyManaflow Band
Manaflow band allows you to trade early and often with [Q] spam harassment to begin your lane dominance early.
WhyGathering Storm
Gathering Storm, like on most Marksmen, empowers you to become a late-game powerhouse able to take over teamfights entirely on your own with 4 items.