Hi! I'm BenLegend443, and I play on NA. I discovered Kai'Sa when she came on free rotation and found out she was great to play, and easier to carry with than Caitlyn, who I previously one-tricked. I enjoy the feeling of playing ranged carry characters, so obviously Kai'Sa is a good choice. I am not a great player, only Silver/Bronze, but that means I can speak for lower elos. I mean like, high-elo players won't be reading Mobafire guides, right?

In the early game, you need to constantly farm to gain gold and experience faster than the enemy. Kai'Sa is one of the hardest champions to stop once she snowballs and she scales into the mid-late game, so it pays off being careful early. Last hit minions and to trade. Your W, , is mainly for marking enemies for your ult, or to finish people off when they run away, as it has an absurd 2500 range. Don't spam Q too often, cuz you'll run out of mana quickly. The attack speed Supercharge gives is extremely valuable in a fight or when you're trying to bust down the turret. Don't push or pick a fight in the early game, since it is important to farm and snowball, but sometimes it's inevitable. The MS boost is great if you're trying to chase down someone or run away. As you don't have yet, would be your main gap closer. Even with this being said, you don't want to push too far or commit to chasing the enemy laner down. Chasing them to their side of bot lane leaves you vulnerable to a gank. You also don't have much range, so freezing the wave keeps you from being harassed and it's way easier to get an advantage over them this way. Since you only have a 525 range AA(the enemy would probably outrange you), freezing is a good technique to utilize. However, freezing is very complicated, so only do this if you're good. Otherwise, don't even try. Farm, poke, and try not to die before you have enough gold to get (otherwise there's nothing to salvage from the death). On your first back, you should be around level 5. This allows you to have enough gold to purchase tier 2 boots and start building . The powerspike you hit is absolutely insane once you get back to lane and hit level 6. This means that you're ready to dive the opponent.

In the early game, you focused on not falling behind and getting your core items. Once mid game hits at around 15-20 minutes, people start roaming and you can start being more agressive. It is still semi-laning phase, so people would still be pushing the lanes and not really team fighting yet. This is where you need to watch out for sneaky plays and mid laner/jungler ganks. The enemy bot lane would probably be pushing aggressively to try and get the first tower down. You have ok waveclear but the enemy can potentially poke you down. Kai'Sa benefits from short trades, like Jhin or Ezreal. If you drag it out too long, you'd probably die. Slow pushing the wave can help build up a large amount of minions. When they walk up to get a last hit, hit them with something that stacks plasma. Ideally, it should be your W but sometimes that isn't possible. You can then tell your support to initiate and you can dive the enemy. Once you kill them, you have a big wave ready to push and wreck the tower. Supports with CC and/or initiating abilities are great since they give the first stack of plasma AND disables the enemy, allowing you to dive them even harder. The standard combo is :

> > > a lot of autos >

If your support is tanky like Leona or Blitzcrank they can tank everything for you and you'll still be pretty high on health. If they are a enchanter, the shield from your ult will tank damage instead. Either way, you'll probably live, as most ADCs have finisher or utility ults(eg. Caitlyn's ), no nukes(like Karthus' ). At this point, they probably can't rival your burst potential yet. Your passive is incredibly painful, so even though the autos do approximately the same damage, your passive gives you an edge. However, you need to be careful about how you use .
A good Caitlyn can predict the pathing of your ult and throw traps to root you for her machine gun crit combo(topic for another day). If it's like a Veigar or something, he can throw up the wall thingy to stop you. Take their abilities and zone of influence into consideration. Do they outrange me? Are they extremely painful up close? How do I dodge their skillshots? These are all questions you need to ask yourself before committing to a dive. In lower elos, people probably don't have the skill to stop Kai'Sa's ult, unless they get lucky. If you're playing Bronze/Silver, just make sure you don't walk into a painful skillshot or CC. In Gold+ you actually need to think about it but you won't be reading my guide if you're Gold+. Get a few kills and you'll be set for the late game.

By this point, the tanks are tanky and everyone has gotten their full build. For a lot of ADCs, they buy armor pen or have mixed damage. You not only have mixed damage, you have a passive that calculates damage from maximum health. 15% of maximum health is a lot. Say he has 5000 health. 5000 x 0.15 is 750. In 2 seconds(the time it takes to shoot 5 times), you would deal about 1300 damage. This is without any abilities, purely autos. Therefore, your goal is to auto as much as you can. However, with full builds everyone does a **** ton of damage(a Karthus does about 1200 damage to you at this point). You will need to be careful.

Whenever a teamfight starts, start shooting whoever you can reach from the back. Constantly use E to make sure you have as much AS(and plasma stacks) as you can. It also gives the added bonus that you gain Kalista levels of mobility. Q whenever it's up. Do this(and save your ult), until the tanks die or until you can mark their squishies. Dive in and start spamming right click wherever, since you'll be in the middle back of their team. Your Q at this point is less useful when your in the middle of the enemy team since it splits evenly among enemies. Simply auto them down and GTFO. If they have a on-death effect like Kog'Maw's or Karthus' , prepare for retaliation. Icathian Surprise can be really painful, and so can Karthus(90% of the time he's going to
ult after he dies), if you don't run away fast enough and/or have Zhonyas. Win teamfights systematically like this. Take down towers with the help of your E. If you haven't fallen behind or fed anyone, you've pretty much won. Good luck on the Rift!