How are you supposed to build Kai'Sa
What's the right way to build her? Is she supposed to be built hybrid in a way you can power up all three stats?
What's the right way to build her? Is she supposed to be built hybrid in a way you can power up all three stats?
Rush 
then
then
then
then 
ap/on hit

1100 damage poke on a champ that can press Q and kill an isolated adc.
Delete ludens and deathcap for wits end
Lord no. Wit's end is weak on ranged atm. Luden's/Rab gives you 2 shot potential on any squishy with W if you get ahead.
Which if you already bought those 3 items... you are.
Its not weak
The MR shred is irrelevant (squishies are already dead and flat pen sucks vs tanks) and the damage on hit is tiny. The MR it gives won't make you the least bit tankier.
You need to get off something like 8-10 autos on one target just to break even with Ludens proc and extra AP. It makes you worse at picking off squishies, lowers your poke damage (which is huge late game) and doesn't even get movement speed...
Kai'Sa has great scalings.... Wit's end does nothing to help that. Hell you even lose ~20 damage a hit off of nashor's tooth from lost AP alone. In reality Wit's end works out to give you about 5% damage... 40% AS and 20-25 on hit. You'd be better off just buying Hurricane/Static/PD/RFC statistically speaking. Hell Stormrazor/ER are much better choices.
A short ranged adc with less movement steroids trying to get off 8-10 autos on a target...... Aint a thing unless you are trying to kill a CC locked mundo... and then you'd be better of getting a damn 
or 

You realize you need like 200 ap tp equal the amount of onhit damage wits end gives you if you did the 15% nashors tooth equivalent. Put it in perspective
Ludens + RDC bonus = 126 AP. Thats 19 damage from Nashor's. Luden's proc is going to deal ~ 160 damage. Passive damage is tricky to calc but ~80+4% miss hp for 4 stacks + rupture 126 damage on Q 75 damage on W 94.5 stronger shield.
Wit's end just doesn't pull ahead of that. It's only good vs a team with juggies if you are gold starved.
Wit's end doesn't synergize well at all. Better off going BOTRK and Death's Dance
On hit. Nashors rage blade runaans blade wits end always