Ok mister meta maker let's break this down point by point
10%cdr for free at 10 min is meaningless? Nobody in their right mind argues that about renekton.
I see you start off with the old "I can't read" approach
Transcendence: Gain 10% Cooldown reduction at level 10.
Level 10 is closer to 15+ minutes, not 10 minutes.
Say I do 400dmg in an all-in burst trade. I'm getting maybe about 20 extra damage.
And transcendence gives you 0 extra damage for a pre 2 item all in. Shoot in that scenario you get 5% increased damage, that is pretty big for a non keystone.
It's good for 2v1 dive potential? You don't need it. If you need coup de gras to kill someone 2v1, you have issues.
1v2, yes I put that backwards but you should've picked that up in context. I have trouble believing you even read it entirely since I was responding to you about triumph, not coup de gras.
This is far from a "peeling" build. This is a build that let's you: 1. Dive into enemy backline, land great burst damage thanks to your high ad - equal to builds with much more ad focus and that leave you squishier. 2. Tank enemy reply damage without getting bursted to 20% hp or less thanks to your massive hp and resistances BUFFED by aftershock to the point you temporarily tank like a maokai. The point is that THIS negates enemy burst damage which WILL logically immediately be focused on you. 3. Live long enough to continue dealing MEANINGFUL levels of damage output. The enemy can either: ignore you, kill some of your teammates, and let you finish them all off or... focus you, waste the entire fight just killing you, and die to all your teammates.
So you dive in, hope to cc a carry, can't kill them, walk around and hope they focus you after you become useless. Do I have that right? Because it sounds like you are almost entirely relying on the enemy being bad or for you to be fed enough to be a damage threat with next to no damage.
Lethality renekton falls off. Sudden impact falls off. Unless you build say 3+ damage items. Not sterak's or titanic - actual damage items. If you build these, you are left insanely squishy. Thus, you are betting on going all-in and 1-shotting an enemy carry. This will generally require a flash vs an enemy team with 2 tanky cc frontliners. Thus you can only fight on a 5 min cd to guarantee effectiveness. Otherwise it's a 50/50 at best. Furthermore, you cannot frontline for YOUR team with such a squishy build. And if you ever get caught out... you die. So. Very. Fast. If you want to do some burst build like this, wukong is a much better option. If the enemy has no frontline because they are playing teemo, yasuo, jayce, or some other squishy toplaner it is fine because you won't need flash every fight to guarantee you can reach a carry and burst them before dying to the enemy's burst since you've built so squishy. Thus why I said... my build is for SOME scenarios; if they have 4+ squishies on the enemy team, I would take a more damage heavy build like you do. Vs 2+ enemies with lots of cc and durability, I'd take my durability, high ad for burst on enemy carries, and sustained damage over yours any day.
You clearly have a fundamental misunderstanding of how lethality works. Lethality itself only gets stronger as the game goes on in terms of value, I don't know what makes you think you need additional items to make it worthwhile. The rest of this paragraph is more relative to elo, you assume the only way to win a game is to 5v5 fight. Good players can easily make use of split pushing to create 1v1's or 1v2's and win that way.
As for your rambling about not being tanky enough, you know I am specifically calling out your build right? Grasp Renekton is fine, this weird scaling bullshit you run is not.
Also, I see you wanna bring rank into this to suggest I'm some lowly know-nothing gold. So lemme give you food for thought. I've found new meta builds and roles before "genius" high elo players. Morgana support, naut support, naut top, on-hit frozen mallet junglers, etc. I've been asked by many people plat+ if I were smurfing in gold and actually a diamond or plat player. And for all you know... this is my smurf account. Don't presume you know everything. I don't run around telling people how to play sona, or what's the best midlane champs and builds... because I don't play too much of that. I do play renekton, I do play toplane, and I do make him work in scenarios where others... even of apparently higher elo would not. Am I the best renekton or toplaner in the world? Not even close. However, I do know a lot more than what you could reasonably assume someone of my apparent elo would know. But back to the final point about high ranked players not doing such a build. Look at renekton's winrate for those elo's. It's abysmal. Then look at my winrate. Much better... despite regularly getting teammates who go 1/7/0 in lane and make the game one that would be ff @ 15 in most people's books.
Me citing actual statistics is bringing rank into this -_- for the love of...
I was going to respond to your 'meta picks' you found, but you just try to brag and brag and brag. I don't care what tinhead Timmy who was hard stuck plat 5 asked you. I have seen people start the season gold, get diamond, and fall back to gold for the end of season because quite frankly you can climb with luck if you are fortunate enough to get carried every game. Even if you were challenger I would tell you your build is bad, Plat+ is literally the standard for statistics on most sites and is considered a decent source of info aside from a few extreme cases. The reason you can win with these build even though it is sub optimal is because in lower elo you can actually take a bunch of scaling runes and not have Jayce shit stomp you or have an actual tank out scale you.
Titanic and sterak's are overrated on renekton. Renekton is a CASTER. He gets his damage primarily from ABILITIES with aa's woven in between them. If he's going to sit there auto attacking, she is outperformed by anyone else who reasonably builds titanic or sterak's. Titanic gives... 35 ad - not an impressive amount. True it gives bonus damage on-hit; however renekton's attack speed isn't that amazing and this damage is largely blocked by armor. Furthermore, this gives you a lot of extra hp to be punished by %hp damage while providing no resistances and delaying you getting meaningful levels of resistance to enemy carries' damage. Thus, it leaves you rather squishy without giving you much in terms of damage aside from the burst from it's active... on a squishy. Sterak's is even worse. All that juicy ad that looks so good? NONE of it buffs the damage from your abilities. And being a CASTER which relies very much on ABILITY damage, this item is fools gold. Sure if you are snowballed and want to end the game asap and need some durability but still want damage it's fine. But in an even game or when behind or barely ahead, the item is a trap. People who talk about renekton being scary never say... oh his auto attacks - they're so broken. They talk about his burst combo. A combo that is buffed by bonus ad... not measly 35 ad from titanic or 0
Do you really not know that your w multiprocs Titanic? Like you're just trying to ignore that part right? Not to mention you can use the auto attack reset with your w ult reset to get like 4 autos of bonus damage off in a second. If you didn't actually know that I'll just see my way out, you have no idea what your champion does and I have no interest in teaching you.
As for sterak's, it is 60 ad late game with a fat shield that scales with hp (just like titanic does, so both work great with your ult) and gives tenacity when popped. As for your claim that it doesn't work with your abilities, I would like you to go read your w description again. Back? Good so as you can see all of these items are meant to give you a huge burst combo with auto w r q auto titanic. Starting to understand why people build him that way?
or
(depending on ap opponents) as core items
or 
depending on how much cc the enemy team has
or 
and 
or 
to finish it off
or 
