G'day. A random person who didn't even touch ranked yet (nor was even able to) here.
Despite of what I just said, I am the kind to research and theorycraft as early as possible, and who isn't scared to experiment since I am not angered nor demoralized easily by anything.

I decided that top lane wack, so I am moving a lot of top laners out of there. First Ornn Jungle (from a local guide), Yorick mid (Q>E>W instead of Q>W>E, runes and items very alike to top), and now this. Kled support

Now why I am even writing this, the way I am writing this, and why did I name the "guide" this way?
"Theoretical" - From what I can gather there is some sense to what I came up with, but...
"Unproven" - As I said, low level man who only could test this in low level draft and only played like 7 games of this, albeit mostly succesful ones

What I want to achieve writing and publishing this is opinions and possible experiences from actual high grade players, so I can refine this possible build into something at least somewhat viable (and even this guide into a proper one)

So as you probably already saw, I placed exactly one item as the base of this whole build: Stridebreaker

Ok so to explain everything, main idea of the build both from rune and item standpoint is simple:
Use mounted Q in any way (with is possibly with a EQ combo) to try and catch an enemy, and if you manage to pull them in, they will become slowed, marked with GW, marked with Font of Life and right in your range to apply PtA and hefty damage with your W , giving basically everything to an ADC (or a ganking Jungler) they would want. If things get hairly and you get unmounted, either go for the funny remount or disengage with unmounted Q . Purpose of things like conditioning, bloodline and triumph is extra survivability so you can make sure you at least don't die in the process.

And here comes in the reason for the Stridebreaker instead of something typical like or : It gives exact stats and has good passive and active effects to support the above gameplan

• Ability Haste always good for Kled
• Can't say no to AD on a bruiser
• AS means quicker PtA and easier remount (exact reason for AS rune btw)
• Health
• Bonus speed on any hit means you can be very sticky and ensure a rell in with Q, or getaway/close the gap when unmounted
• Active slowdown effect ensures that the target stays in place for as long as possible for the kill, or allows for a safe disengage for you and your ADC
• 2% bonus speed per legendary makes getting in/out and dodging skillshots easier the later the game goes

Everything else after Stridebreaker is based on gamestate. Steraks+Titanic for survivality (EDIT due to 12.3: due to the new change of it's shield scaling only of your bonus hp, and not of enemy hp, you should continue getting bonus hp items after steraks, with hydra being a must to regain AD. and...), Black cleaver if you see lot of armor going around (or took the above. thanks to "buff" even without stacked armor it should give you a good chunk of everything), Serylda to double down on slows if ahead, Umbral Glaive if against a trapper, Chains against a fed enemy, Death Dance (and Guardian Angel if the situation is that bad) for some anti burst 12.3 changed the item to cater more to burst mages/assasins, but I suppose Guardian Angel is still an option, Lord Dominic and Blade of Ruined for more dedicated anti-tank, Wit's End or newly buffed Maw of Mal for when magic is a problem

12.3 initial update:
well this one happened at just the right time eh?
so
till now you could go Steraks+Titanic and go whatever due to how the initial worked. Not now tho. those changes lock you into 2 choices: A full hp build, or a full ADC like build, shown in example builds
BUT I haven't yet tried them, since technically patch ain't out, so don't take my word on them at all. I will try to once it is, and see if anything can be improved

Yes.
but no.

One last thing I want to mention is the Ult
As you can guess, being a semi-global ult it can impact the game in many ways. Early on it can be used as a discount recall-teleport into a possible kill for both of you in lane, and due to the fact you tend to stick to your ADC, there will be always someone benefiting from bonus speed from following you. It can also be used for roaming as a pair if a need and occasion arises to visit mid/some spot in the jungle. Post-Laning phase once you hit 11 it can be used lot more agressively and to bring your whole team to a spot that needs to be visited, like a dragon or the frontline


Ok that's it now.
I will refine and update this thing as time goes and I play more games to understand matchups better, and of course, as mentioned earlier, I hope for your input on what could be mentioned/improved.