Kai'sa fun facts (As of current PBE patch).
Q. Works with Muramana. Yes. All 12 bolts potentially. On a single target. It even counts the damage on initial cast, so you don't get it significantly reduced by the sheer volume of mana you just drained by proccing it 12 times at once. If she catches you out alone with Muramana built, she can and will 1 shot most likely, as she will be able to do 72% of her mana bar as physical damage to you, on top of the base and ratio on her Q. You may just see trollish double-tear builds on her just to turn that 2400+her base mana into 1720+ physical damage on her Q just from the Shock passive. Probably toss on a Trinity Force and a Duskblade to just maximize the 1 shot potential, while grabbing Zerkers to finish it off and ensure she has all 3 evo passives (As Seraphs will trigger W evo passive by itself, and Trinity-Zerkers has just enough AS to skim her over the limit later into the game once she is level 14-15ish). With a full build of this idea (muramana abuse) she has 3678 mana, for 2648 physical damage from the Shock passive alone. Not even counting her AD/AP ratio, or her base damage. This is quite possibly the single highest non-ultimate damage skill in the game. Muramana gives just under 100 AD with this setup, while Seraphs gives just over 160 AP. This is setting up for a total of 3616ish damage before resistances. Even a 200 armor tank will take a chunking from this, at 1200ish damage. You can potentially cast 3 Qs in the duration of Presence of Mind, so if you get an assist from say your W, you can then pop off and rain unholy justice from above. Even if you decide the Seraphs is a bit too much of a streach goal, Q still gets 820 physical damage from just Muramana+Trinity+level 18 base mana shock proc, so you still can end up quite scary with just the basic Muramana.
Passive evolutions - Takes exactly 100 (+100% for AS) of each stat. She gets 1 AD per level (that counts toward the evolution, so you can potentially just skim over the mark if you have something like Gunblade+Duskblade for a bursty assassination pattern), and she gets just shy of 30% AS by level 18. Rageblade-Bork-Zerkers gets you E Evo by around level 9-10, while also setting you up to get both Q and W evo with Gunblade built. Q Evo triggering once you finish the cutlass for Gunblade (Or both longswords anyway), while W evo taking the finished Gunblade.
Q AD and AP ratio - Best case scenario, you can get a 12 hit for a base of 472 with a ratio of 1.72 Bonus AD ratio and 1.29 AP ratio, as physical damage. As her Q counts as single target for Muramana, odds are it does the same for Gunblade healing (haven't tested that yet). Squishies beware being by yourself, and even without that she can heal like mad from Q gunblade on a minion wave.
Overall, Kai'sa may just be the most build diverse champion in the game.