As always, things get kicked off by the cheatsheet. You give an overview of all possible runes, summoner spells & items that can be taken. Usually this information is accompanied by some short notes on when to take what. Of course, you cover this in the main guide already, but it can be beneficial to add some notes anyway.

Second, your full build examples. The damage, AP & AD builds are all quite clear in what they are meant to accomplish. However I am not sure what the tanky & balanced builds are for? General tankyness? A balance between damage and tankyness? Again, a short note could do wonders here. Some pros & cons repeat each other and some are.. obsolete…
Kicking off with cons:

• “Missing E can mean certain death in some lanes.” And “Misusing W will lose you matchups”. Can technically be merged to “Missing or misusing abilities will lose you lanes”. Not sure if this is a champ-specific con though. Misusing abilities on any champion can be detrimental.
• “Though his scaling is decent, it gets very difficult to 1v1 lategame champions in Death Realm”. Perhaps you can change this one to “Cannot 1v1 lategame champions”? 1v1ing is not limited to Death Realm and you already mentioned that his scaling is decent in pros
• “Very difficult to play … sometimes” Aside from a typo (“Q and E can be difficult to lane sometimes”) you might want to split these two statements into “More difficult to play at high elo” and “Q and E are difficult to land” (note: what do you mean by “high elo” here? Is it applicable to the audience you’re trying to reach?)
• “Some matchups are a nightmare to deal with” This one is rather vague, are there many hard matchups? Lots of hard counters? Just a weak early game in general?

Then hopping into the pros:

• ”Guarantees 1 person’s death with ult” disagree here. If you are behind you might not be able to kill anyone, even in death realm.
• ”Snowballs incredibly hard and scales better than most bruisers” & “Unkillable monster when ahead”. I feel like saying he snowballs well & that he’s unkillable when ahead is the same thing.
• ”Useful when behind due to his ultimate” you forgot a + here.

• At Q: “as most people won’t react to a Flash Q.’’ In this context, shouldn’t it be Q Flash rather than Flash Q?
• At W: “And you have low cooldowns so try not to waste it when you are on autopilot”. What are you trying to say here? Of course, wasting things is never good, but usually one of the arguments to not waste stuff is because it has a high cooldown.
• At E: You mention “not missing E”. Maybe it would help to give some tips on how not to miss this thing. It has the speed of a snail and is arguably one of the easiest skillshots to dodge in the entire game.

• You say not taking Flash is a very bad idea but at Ghost you say you can take Ghost instead of Flash.
• It is a bit vague when you can opt into Ghost. You mention “killable ranged laners and a team that can kite you well”, what ranged toplaners do you consider to be killable?

• You do an alright job of explaining the individual rune choices, however you do not explain when to go Domination vs Sorcery vs Resolve secondary.

• A bit confused at Mercury's Treads. You mention stuns and then list Ryze as an example, but Ryze doesn’t have a stun.
• Hextech Rocketbelt: Do not say “This item is great!” shortly followed by “It’s situational”. I think it is better if you mention “This is a situational item. Get it into more mobile teams as your first item”. After that you can add some flavoring by saying its cheap, that it has all the stats you want and that it scales very poorly.
• Banshee's Veil: Confused by “what the item lacks for in AP”. It literally has the second highest AP of all the items you list here so this statement is simply not true. Perhaps you mean damage?
• Morellonomicon: “Lethality” always reflects flat armor pen. This can be confusing, since we are talking about flat MAGIC penetration here. Unfortunately flat mpen doesn’t have a fancy word so up to you what you do with it.
• Dead Man's Plate: A random sentence: “The movement speed is.” Although this is iconic for DMP I don’t think you meant to say that :p
• Sunfire Aegis: You basically say that you don’t think this item is worth it. Why keep it here? Just kick it out of your guide.

• First sentence: “Early game lane bully”. Why isn’t this in your pros/cons section? It would fit right in there!
• You randomly link a video to a Darius guide here. Why? If it was Morde content you could just throw it in. It might be a good idea to explain why you are linking this guide here.

• The video you link here is the same one as the second one in the early game section.
• At the teamfighting part you mention peeling, however in the pros & cons section you mentioned that your peel is bad. On a second thought, you can press R on that assassin/diver and thus saving your ADC so your peel aint the worst compared to other juggernauts.

Warding & Macro

• This is the third time you link the D2 Darius Live Coaching session. I require an explanation.
• There is also a random (part of a) link after this video.

Rhoku’s code
I like seeing a mentality part in the guide. Many people forget that mentality can win & lose games. Raised eyebrow on the first point though. Your guide got a nice look overall. I see you like red a lot, but you managed to add some greys here and there to keep it more Mordekaiser-like.

Now let’s kick off with the biggest issue in your guide: the presence of centered text. Single sentences, quotes headers images, stuff like that can be centered. But centering entire paragraphs/sections is BAD. Why? It makes the text unnecessarily hard to read because not every line starts at the same position. The haphazard pyramid that is the result of centering the text doesn’t even look good.

You start your guide with about me & contacts. This in itself is fine. However, I am concerned with the amount of space the contacts section takes up. This is partly causes by the size of the images, but can be resolved with some code. You can put the images & links under them at the right or left side of the guide and put the text next to that.

The pros & cons looks good. Tiny nitpick: perhaps you can put the dark star mordekaiser splash in place of the infernal mordekaiser splash, since infernal mordekaiser is already in your banners & guide theme.

Abilities looks good, good usage of a template here. Recolor was successful and matches the theme.

Summoner spells. I get the idea, it looks good, but I am a bit overwhelmed. Maybe it is the lack of open space (you missed a spacing row between Flash and Teleport btw). Maybe it’s the red that’s so overwhelming. Maybe it is this huge red ad that’s sitting at both sides of my screen. Anyway, you could make this more like your items section (I’ll get to that in a bit).

I’m not sure why, but some runes in your rune section are larger than for no apparent reason (like Legend: Alacrity). The text here is centered too for some reason. I think it would look a lot better if it wasn’t.

If I had to name the best-looking section in your guide, it would definitely be your items section. It is just… perfect! Just the right amount of open space & the right colors, it is a treasure to look at & read.

You did miss a space in Cloth Armor description (“all require Cloth Armorto survive in”) and at Hextech Rocketbelt “You mostly want to be getting into more mobile teams” seems like it should be “you mostly want to be getting it into more mobile teams”.

Your gameplay chapters consist of some big walls of text. It might be helpful to split some of these blocks into smaller paragraphs so it gets easier to digest the information. I would also refrain from using different colors here: you got some headers/dividers in green/yellow/orange/etc which clashes with the main theme.