Thanks for the feedback. This was my first guide and I forgot to update when I learned about the CDR cap. I haven't written much because I'm not familiar about formatting. I will be updating this guide after learning some more about the game. Again, thanks for the sugestions.

Well, he said criticism welcome, so I gave it. He has an idea of how to play Xerath, but it's not really concrete and he misses out details. Hopefully I've shed some light.

LoL, Sirell just dropped the hammer. Take it easy big guy.

I'm aware that you didn't ask for a review, but since I was going through your guide, I thought I'd use my formatting to make it easier for myself anyway.

Cheatsheet:

Summoner Spells -

Ideally, you don't really want to even be in range to use Ignite (600 units) of your enemies. Look at your spells: Q - 1100 range, W - 1100 range, E - 1050 range, R - 3200-5600 range. So Ignite goes completely against your entire kit.

Barrier, Exhaust or Heal (and maybe Cleanse) are all better options in the event that an enemy does get too close. Your reasoning against Barrier is flawed.

Barrier and Heal is what you need to survive an all-in, usually from nuke/burst champs like LeBlanc, Ahri or Katarina.

Exhaust is for a similar purpose as the above and is usually taken against enemy champions which also excel based on AS or autoattacks, like Yasuo or Riven. It lowers their killing potential and can either let you turn a fight or escape more easily.

Clarity is a trash summoner; don't ever take it on any champion. And if you know anything about Xerath, you should never have suggested it in any case. All the other spells aren't really worth considering either.

Runes -

Your seals are probably better off being just one particular stat. You don't get a lot by splitting them the way you do. Most people tend to go for scaling hp in seals or just flat armour.

Glyphs are better off being Scaling Ability Power, since Xerath is mostly about scaling into the later game.

Masteries - Expose Weakness is kind of a useless mastery point for solo laners in general. I'd say you're better off taking a point out of Sorcery and Expose Weakness and putting it into Butcher and Feast for better lane sustain. On a similar note, you can omit points from Fleet of Foot and put them into Phasewalker , Alchemist and Culinary Master if you don't want to get Runic Affinity .

Items -

I don't get your obsession with so many CDR items. There's a 40% CDR cap anyway. So taking the 3.75%/5% from masteries, 20% from Morellonomicon/ Athene's Unholy Grail, in addition to the 10% from the likely Blue Buff that you get in-game, you already have ~35% CDR, thus, Ionian Boots of Lucidity aren't really a valid option. In the uncommon occurrence of purchasing double CDR items, you immediately cap 40% and there's even less need to buy Ionian Boots of Lucidity. Put simply, that choice of boots are an unnecessary buy. Sorcerer's Shoes 100% of the time, unless you absolutely need Ninja Tabi or Mercury's Treads.

You should probably format your cheat sheet a bit better so that it's not just rigid purchase orders, something like this:

Starting Items:
Doran's Ring + 2 potions.

Core Items:

Morellonomicon/ Athene's Unholy Grail
Zhonya's Hourglass/ Rabadon's Deathcap
Void Staff
Sorcerer's Shoes

Situational items:

Luden's Tempest
Banshee's Veil
etc etc

Another thing is that you shouldn't ever need to start with two mana potions. Something is severely wrong with the way you're playing Xerath if you're getting mana potions; you shouldn't even need them. Health potions/biscuits are much better regardless of any laning.

Skill Sequence -

QWQ is fine, but as a note, having E means you're secure from early ganks, as well as early kill pressure when setting up your own ganks. You can just stun the enemy and walk safely back to your tower or stun the enemy when your jungler is coming for the gank when you are level 3. It will be better if you make that known to your readers that that is a possibility to keep in mind.

Written Content:

There's actually very little in the way of written content, but a large majority of what you write seems to be filled with misinformation. For example, you ALWAYS should get a Void Staff if possible, since all champions start with base magic resist and people will pretty much always be building magic resist anyway. I've already mentioned the objection to starting with two mana potions.

You don't cover what enchantments you should actually be getting (and in fact, this is quite crucial at times), the answer to which are either Enchantment: Homeguard or Enchantment: Alacrity (usually Homeguard).

You also miss out mentioning situational buys like the early choice of buying a Haunting Guise to assert lane dominance, or a Banshee's Veil against poke comps, etc.

Some of the matchups just plain out lack depth or are just plain wrong. Vel'Koz doesn't outrange Xerath, it's the other way around. Xerath also has counterplay tools against a Katarina, namely saving your E until she is channeling her ult or just in a really bad position for you and stun her while her Shunpo is down.

Verdict:

Has a long way to go. Tends to be filled with misinformation or lack of depth and frequently gives the impression that the writer does not understand the champion enough to be writing a guide.

As a (not very high elo) Xerath main, I actually liked a lot of your ideas; however a couple of things kinda made me scratch my head.

First of all, you recommend the Athene's + Morello build for 40% CDR, mana regen through the roof and some nice AP (I usually only go for one of these), but at the same time you have the Sorcery mastery for 5% CDR and even worse, Ionian Boots instead of Sorceror's Shoes, which puts you way over the CDR cap. I think going for both Athene's and Morello makes the latter two unnecessary, or you could go for a build with only one of those and possibly Ionian, although even then Sorcs are generally preferred.

Your choice of Ignite, as well as the explanation, is not optimal in my opinion. Ignite is usually taken on champions looking to get early kills and snowball off of it which Xerath likes to do, but when I play this is through poke, occasional e-w-q combos and finishing off with ult. Bringing an opponent low as this champion usually isn't from within Ignite's range - especially not with ult ;) - and if it consistently is then in my opinion you're not utilizing Xerath's range and damage to its fullest.

My personal preference, ignoring Flash, is Barrier and sometimes Ghost. I can't tell you how many plays I've made with Barrier in all stages of the game against dive-style champions - Zed, Lissandra, Katarina, Leblanc, even the occasional jungler like Lee Sin - that Ignite has never done for me. Although its utility usually doesn't match Flash, you only get one every 5 minutes so I think Barrier is the best choice.

From a design perspective, you should put in some visuals in the later sections to add interest - I think I was only able to read through it because so much of what you wrote gels with what I already knew. Overall interesting guide, and good luck with it!