Leaving a comment if you like this style of video really helps in making more, had quite a lot of views recently on this style of showing off a fairly new thing + a full game
Conqueror has been waiting for an AP user to abuse this, and I think Kat is one of the primary candidates, she gets to keep the full 8 second buff/reset window (suspect this may be nerfed) as she is melee, and she makes very good use of all of its aspects.
So why Conqueror?
* Other rune choices suck, electrocute is taken but this is super nerfed and hard to proc off cooldown on kat
* Conq gives AD/AP stacking up to 5 times, this is just really high value with Kat's high ratios and she has no problem stacking it up quickly, snowballs extremely hard if resets start to go off, the true damage and healing is all just really good value
* Better all in with the death dance build as a bruiser type while keeping the burst, much better 1v1 build
Why Death Dance?
* Passive Stacks with gunblade! You can expect full hp heals from dagger procs or gunblade active, crazy along with rav hunter on top as well
* Simple damage calculations, Kat has VERY high AD ratios and easily puts out the most damage with abilities even if you can't auto people with this 2 item spike
* Lets Kat stay close combat 1v1 with many champions, gunblade-DD is still AD items at the end of the day, and if a tank wants to stay in your face you will just auto attack them to death
Problems with build
* DD is pricy, at 500 more gold than morrellos. I consider this a worth trade off though, death dances build path is nice (better than oblivion orb or trying to put together an hourglass)
* Weaker lane quick trades with no elec, this honestly is not that much of an impact and a good trade off
* Late game deathcap isn't quite as good an item, deathcap is somewhat of a luxury item on kat in the first place though and you can pick up another defensive item like veil and still be doing amazing lategame damage because you have the raw stats and resets to not need a deathcap