Kog'Maw has no mobility, so once Kai'Sa dives with Killer Instinct (R) and stacks plasma via Void Seeker (W) to detonate with Second Skin (P), he simply gets deleted.

Jinx also lacks mobility, so when Kai'Sa initiates with Supercharge (E)'s stealth and Killer Instinct (R)'s dash, she can't leverage Super Mega Death Rocket! (R)'s range and gets caught.

Twitch has short range before Ambush (Q), so in lane Kai'Sa gains the edge with Second Skin (P) plasma stacks and counters all-ins with Killer Instinct (R).

Smolder is extremely weak early before stacking Dragon Practice (P), so Kai'Sa crushes the lane with Killer Instinct (R) all-ins before he scales.

Caitlyn's longest range plus Yordle Snap Trap (W) and Headshot (P) poke chip Kai'Sa's health before she can build Second Skin (P) plasma stacks, stalling her scaling.

Kai'Sa's ability evolutions depend on stat thresholds rather than a specific level. Before she has enough stats to evolve Icathian Rain (Q) and Supercharge (E), she struggles to trade head-on into Draven's powerful early Spinning Axe (Q) basic attacks.

Lucian's Lightslinger (P) double tap and Relentless Pursuit (E) dash give strong early burst and mobility, pushing Kai'Sa out before she stacks Second Skin (P).

Miss Fortune applies constant pressure with Double Up (Q)'s bounce poke and Love Tap (P) empowered autos, and shuts down Kai'Sa's scaling with Bullet Time (R) in 2v2s.

Samira blocks Kai'Sa's autos and Void Seeker (W) projectiles with Blade Whirl (W), and her lifesteal-based all-ins win the lane.