Katarina remake:

The recent change showed that Katarina is in need of making her skill cap higher and more varied, the only factor contributing being *not* disabled by an ultimate, which is too unreliable over all ELO's, being too detrimental in peak low and high ELO.
What I believe the solution to making Katarina both *more fun* and *more difficult* to play, without making her stronger for anyone else than those who would grasp her concept.
Current Killer Instincts only modifies Shunpo to work in 2 different ways. I propose to go further. By levelling up Killer Instincts, you would be granted 2 "types" of Bouncing Blades, Shunpo's *and* Death Lotus.

Here's how it could look like.

Killer Instincts:
Passively grants bonus damage to Katarina's abilities and autoattacks. The skill will have a cooldown of ~14-6 seconds. The cooldown is meant to be high enough to use it only once per combo, more with Voracity.
Depending on whether or not Katarina uses Killer Instincts in combination with any of her abilities, they work differently:


(No KI)Bouncing Blade : Damage Reduction per bounce is removed, Grevious Wound is applied each cast, duration scaling(2 / 3 / 4 / 5 / 6). Otherwise no change.
(KI) Tagging Blade - Deals 80 / 120 / 160 / 200 / 240 (+1.0 bonus AD, +0.6 AP) damage, but hits only one target, tagging and revealing the enemy for 2 / 3 / 4 / 5 / 6 seconds. During that time, Katarina may use Shunpo / Blink Strike to the target disregarding casting range. *May* tag allies.

(No KI) Shunpo - 15 / 20 / 25 / 30 / 35 % Damage reduction is now normally applied. Shunpo lands Katarina in front of the target. During the 3 seconds, Katarina ignores unit collision. Otherwise, works as usual.
(KI)Blink Strike - Slows the target enemy's movement speed for 40% for  1 / 1.5 / 2 / 2.5 / 3 seconds. The slow is 50% stronger against targets affected by Grevious Wound. Katarina lands behind the target.

(No KI) Danse Macabre - Deals current damage in 1.5 second, but to only one target, prioritizing the low HP target.
(KI)Death Lotus - Works as currently.

How does that make things different:
Basically, the skillset is now split into two. Bouncing Blade gets a single-target counterpart Tagging Blade, allowing for mindgames, more efficiency in a 1v1 situation and some surprising initiations/escapes. It is now much more useful for harassment in lane and a great finisher. Alternatively, you got the usual BB which is a much better teamfight poke, group anti-heal and a farming tool.
Shunpo now has a partner Blink Strike - It's basically an offensive, soft CC version of Shunpo, which allows one to set up Ultimate, single kills that much easier. Alternatively, you have the teamfight version Shunpo, which grants you protection and boosts your defenses regardless whether escaping or initiating.
Lastly, Katarina's ultimate would be split into two - Death Lotus would have a sister Dance Macabre, which deals only a third of the damage Death Lotus can, but it's more focused and quicker. Alternatively, you can use Death Lotus, which is more risky, takes twice as long, but is three times more efficient damage-wise in full effect.

Some Synergy would involve using Shunpo + Death Lotus in a teamfight, Blink Stike + Danse Macabre on a single target, Using Tagging Blade in combination with Shunpo/Blink Strike in a chase situation both ways or using Bouncing Blades in combination with Blink Strike.
HOWEVER - You cannot use Tagging Blade AND Blink Strike at the same time, nor can you use Blink Strike in combination with Death Lotus, making you reliant on killing your target(Voracity cooldown reduction tick) quickly to continue doing your combo. Cheap, long-range initiation comes at a cost.
The ultimate split would address her issue of being counterable by CC in individual situations, while still remaining counterable in teamfights.