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Awesome guide Tipakee, keep em' comin'!

I havent decided if i should buy him or not im kind of a new player and some of the terms your using confuse me a friend got me interested in the game 2 weeks ago and i have been non stop playing it i really love this game and im kind of obsessed with this champion i have been doing alot of guide searches tips and tricks and this is the most detailed and good guide i have seen so far but i dont understand alot of what was said it still helped alot im sure my friend will get me associated with the LOL talk and things thank you for the guide i really enjoyed reading it but i am not high enought lever to use runes and idk how to use masteries based off my champions help???

Hey Faze here is the real quick and dirty math I checked with on the forums. I also ran a custom and pressed the character tab to confirm.
With a void staff you get 40 % pen. Now apply 15 % from talents to the remaining difference of 60% on the enemy to reach 49% magic pen. Now take Xeraths 30% into account and apply that to the remaining amount of magic resist and you get 64.3 % Magic Pen. Magic pen stacks multiplicatively not additively so these values as expected are less than 40+30+15.

just bought xerath and im loving him. what makes him so fun is people expect him to be bad. a question for the writer though, how would the magic pen work with his passive? say with void staff, does it stack onto each other? 40 + 35 would make 75% magic pen at max level?

Smart casting is needed guaranteed full burst.

Hey admiral, I have noticed pretty similar things in regards to ROA and Ryjals over the past couple of weeks. I'll update my item section to reflect that. I still feel that Morrelos is amazing and I don't know were you're getting mana regen unless you get supplied the second blue buff with just a cata passive for regen. I'll fiddle with your build because Xerath can snowball real well and morello's doesn't offer the same AP benefits as other items. In regards to WOTA, I think it is still a very strong item given how much poke (free damage) you can do. This item can enable you to never have to go home, even if you where brought low in a fight. However it is not absolute "core" because some games call for differing builds.

I indended to write a Xerath guide because i saw so many free weekers misusing W and getting themselves killed for it, but your guide covers most aspects. Here is where i feel you could change it. Xerath has massive level 6 burst and can pretty easily get fed, off of the side lanes if the enemy mid is playing passive or is Kassadin. Champions who get fed early benefit greatly from Rod of Ages, and Morello's Evil Tombe is generally not a good item (CDR comes from Blue pot and Blue buff). My build is Dorans > Catalyst > Boots 1 > Rod of Ages > Sorc Shoes > Deathcap > Zhonyas OR Banshee's (depending on enemy comp, more armor never hurt but if they are really AP heavy i want Bveil now) > Ryalis / Void Staff (I get both but the order can be changed).

Generally i feel that you should not need Will of the Ancients because you should not take any damage unless they jump you with 5, and in that case Zhonyas will be more useful. Its good for people like Brand and Cassiopeia who have to stay close to the fight and take damage as well as deal it, but Xerath can fight from over a wall, or behind his tower, and still be useful to the team. Ryalis is amazing because DAT AOE SLOW from your ult can shut their teams movement down for 6 seconds if you refrain from spamming and space them out. But generally i think that your item build is underpowered. RoA is so good if you can get one by 14-15 minutes (and Xerath ususally can), and Morello's is inferior to DFG in almost every way, but Xerath CANNOT use DFG because of the range thing, so neither is an attractive option. Better off with more AP and beef, that way if you do get dove you wont just die, but will be able to kite them.

Hey Synaptic thank you very much for your input! I will have to disagree with you however on the Ionia boots. If you are building a Morelleos they are not very good. You will be paying for 4% CDR that will be completely worthless. Additionally you should be supplied blue buffs very frequently, and if you die with the blue buff a blue pot should be chugged if a fight is going to break out. I cannot justify spending 700g, on 11% CDR, when you will have very high amounts of CDR already. Sorc shoes may have small marginal benefits because you have so much % pen from your W, but that is better than more CDR when you are already capped. Also you do not have high magic pen from W until late game. I personally think Merc treads is a better second option for boots than Ionia boots.

As for the MR or armor argument. You need to look at the enemy team. In an ideal world you would never build any defensive items and just assume "ill never get touched." However this rarely plays out, and some defense is needed. I find that my passive gives me alot of armor, late game until i get MR items i have 30 MR and 115 armor. That is why I suggest getting MR, also it is alot easier to peel Melees off, rather than casters. If Yi, or Xin, or whoever charges in at me, I immediately etheral chains, and ult/Q. Than I immediately cancel Locus and kite my ass off. If you are bursted down by a melee AD and you had proper positioning in the back of the fight (as in 1000+ range from the front line) and properly stunned and kited the enemy, you honestly can blame your team (Assumeing it was a teamfight, if its the laneing phase the melee should never get in the 500-700 charge range). I honestly believe that a Xerath with 100+ armor, and flash should not die to any melee because they should never get close, or be able to stay on Xerath long enough.

TLDR, I do not think Ionia boots are good if you are getting Morellos.
Armor is mostly taken care of by your passive, I said to usually build a banshees because it suppleis health/mana and MR. Late game Xerath has high armor values, not high MR values. Also mages are just as likely to get on Xerath as AD's.

With all that being said, I don't recommend building a banshees if the enemy has no magic threat and you need armor or health. The suggested items are just that "suggested" not definite for 100% of games.

Thanks for the feedback, also I encourage others to discuss this topic or other points of interest. Thanks again Synaptic.

I find the full 40% CDR to be very useful on my Xerath; it helps you deal with the hectic shifting of teamfights better because it isn't as huge a deal when you miss something. This is easily attained with Ionian Boots + Morello's, no runes necessary. I feel that Ionian > Sorceror's, especially after late game, when you already have 40%(Void Staff), sometimes 49% (Void+W) magic pen and the -20 pen you'd get turns into only a -12/-10 pen advantage. I have also tried Frozen Heart, but it didn't quite work for me because it didn't fulfill its other job - deal with enemy DPS.

The suggested Banshee's or other MR items round out this build very well. However in most all fights, except perhaps something like an AP Kog'maw, you should never be in spell range anyway. Again it is still useful against assassins like Kassadin or Katarina, and I think it still deserves consideration in the main build. However, in many games you'll face a fed Yi or a fed Jax or a fed Xin that can just ignore everything else and head straight for you. In this scenario, many times your team and your flash just aren't enough, especially in instances when you get jumped while trying to farm. So I feel that Xerath definitely needs one more escape mechanism. Exhaust would handle this nicely without changing the item build at all, I may test it out a bit and see if I find it more useful then teleport. Personally I used Zhonya's to handle it. Although you shouldn't have to use it in a team fight because that would mean poor positioning, it does allow your cooldowns to come down for that one extra EQ when you get caught. Not only did I pick up many kills on overconfident melee champs this way, but it gave me maybe an extra half-screen worth of escape time during that extra stun. Like I said I also tried Frozen Heart and it didn't due much - Xerath already gets armor but is a little low on health; I feel like a health item would work better with that passive if you want that extra survivability. Thus Rylai's would serve nicely - slow from the E assists in escape, health assists in general living. I would recommend any of these items or spells over Banshee's in most games when you face off against any gap closer and no partial or full-AP assassin, as magic resistance is usually not a big issue for Xerath.

TLDR: Ionian > Sorc's, Zhonya's/Others > Banshee's