I'm a Diamond adc main who's played a lot of Kai'sa. Even hit top 100 on her. I've coached many players in the past and have played League since season 2.

Kai'sa a short ranged adc who like to burst targets early via HoB and W, and later on kites and assassinates her targets.

She has a short range which can be troublesome against champions like Ashe, Caitlyn and Brand. However she's very strong lategame and can easily solo carry a game if played correctly.

Kai'sa's Q is very good at killing low health minions. It's also amazing for bursting single targets due to all missiles hitting the same target. This is called an "isolated Q".

Kai'sa's W is amazing for spotting out enemies like checking if they're doing dragon, checking if enemy blue is up to predict jungle pathing and more. Kai'sa's W deals more damage to targets with a lot of passive stacks. Popping your passive with your W all,ows for great burst, surprising your enemy.

Kai'sa's E is amazing for kiting and extended fights. When evolved, it turns you invisible. This can be used before dashing with your ultimate. Allowing you to arrive while invisible. Meaning the enemies won't see your arrival.

Kai'sa's R has many used. You can use it to simply gain a shield, to dodge sillshots, to escape over walls and to chase enemies. Very dynamic ability which allows you to adapt to every situation.