Lux Support vs Kai'Sa ADC Matchup

How to play as Lux

Hold Light Binding(Q) defensively when Kai'Sa has engage support backup; if Kai'Sa casts Killer Instinct(R) to close the distance, buffer your Q directly at her landing position to trap her in place.

Lux has 21 base armor and 580 base health with a flat 10-second cooldown on Light Binding(Q), leaving her defenseless against dive burst when her root is on cooldown.

Killer Instinct(R) can target only a visible enemy champion marked with Plasma, and its range increases with Kai'Sa's rank.

How to play as Kai'Sa

Do not hide behind a single minion against Lux; position diagonally or behind at least two minions so Light Binding(Q) cannot reach you.

After Lux misses Light Binding(Q), look for a short trade only if the enemy carry and support cannot answer; Lux still has Lucent Singularity(E) and Prismatic Barrier(W), so do not treat a missed Q as a guaranteed all-in.

After Lux misses Light Binding(Q), use Killer Instinct(R) only if she is visible, Plasma-marked, and within your current rank's range; choose a landing angle that avoids her follow-up spells rather than assuming she cannot respond.

Lux's Light Binding(Q) roots up to two consecutive units along its projectile path, meaning standing behind a single allied minion or support does not protect Kai'Sa from being snared.

Supercharge(E) grants burst movement speed (and brief invisibility post-evolution), allowing Kai'Sa to sidestep linear skillshots like Light Binding(Q) and Final Spark(R).

Sources

These notes come from LoL Wiki, r/kaisamains, and r/lux, checked against the champions' abilities.