This is my first guide here on Mobafire so please leave comments that will help me to improve the guide.

Now let's begin, Xerath is a very powerful early game champion when played properly and an absolute menace when he scales into the late game. I have seen many guides on this site for Xerath but none, I believe, really seemed to capture his true strength so I decided to share my build with the community.

Pros:
-Solid Burst Strength
-Incredible Poke Range
-Good Farmer
-Good AoE in teamfights
-looking like a boss while wreckin shop
-hard to zone out

Cons:
-squishy
-has to be rooted in place for full range and burst potential
-no one skill cc
-no escape mechanism

Both the masteries and runes I have chosen are there explicitly to boost Xerath's damage output. As a pure caster with sufficient base mana Xerath really only needs one thing, MORE AP. Ok that's not entirely true but you get the point.

Now I've heard the argument that Ignite is a must on Xerath for early lane dominance but this is not true, his poke is amazing and your lvl 6 burst should be more than enough to finish anyone opposing you.
If you find in character choosing that you will be facing a Vladimir or a Dr. Mundo please pick Ignite instead of Ghost. Neutralizing your opponents only real way to fight back is more important at this point.

Now I shouldn't have to put this here but too many times have I seen AP carries cry about their "overpowered" lane opponents, yet when I press tab I find that they are losing in cs to their opponent by nearly 20 or more creeps. LAST HIT EVERY SINGLE CREEP. If you aren't at least on par with your lane opponent in farm then you're doing it wrong. Farm is extremely important as it takes about 11 cs to come up with equivalent gold to 1 kill and lucky for us Xerath has excellent farm. Your Arcanopulse is going to be your bread and butter all game and this begins with your creeps. Xerath is somewhat unique in that he can both farm and harass his lane opponent at the same time. Line up your opponent behind a wave of weakened creeps and pop your q. This will allow you to both get the cs and harass at the same time. Not only this but you can do it from crazy range as Xerath's Arcanopulse has naturally good range and when you engage locus of power you can tear up your opponent from the fog of war behind your creeps.

Pre-level 6
Xerath has quite good damage output early so you shouldn't have too much of a problem at least keeping up with your opponent. At level four if your jungler is ready allow your opponent to push up the creep wave if you can. When your jungler is in position flash forawrd and engage locus of power, tag them with mage chains and aim your Arcanopulse. If it lands it will deal significant damage and cause them to become stunned. This will give your jungler time to get on top of them and begin to do damage. Now unless you need to, do not disengage locus of power as it gives you magic pen and at this point you should still be within your Arcanopulse's extended effective range, line it up and tag them again. This results in a kill 90% of the time when executed properly.

Lv 6
Now if your jungler is already engaged or you don't have a jungler because you're not level 30 wait until level 6. Once you have your ult you're ready to take your opponent down. Give him a little harass, down to about 60% health and use the following combo. Flash forward engage locus of power and tag your opponent with mage chains. Now use your Arcane Barrage one time to get the stun on your opponent. As soon as the stun lands use your Arcanopulse as it will be almost impossible to miss. Follow this up with the last two hits of your Arcane Barrage and if they aren't already dead finish them off with one more Arcanopulse.

First Back
Now after you either kill your lane opponent or force them to back push the lane and go back yourself. Begin to purchase your way into your build and for gods sake if you have the extra gold pick up a ward or two, I don't care that your build is expensive and you're the AP carry it is still your job to ward along with everyone else. Map awareness wins games people. If you need help with ward placement there are several guides on this site that can be of huge benefit to you.

Start off poking opponents with Arcanopulse. Then when you think the action is going to start you need to make a decision. Am I positioned correctly to engage my locus of power now or am I too far away from the fight to make it count, or even worse am I so close to the center of the fight that I will surely make an easy focus. Either way once positioned correctly engage locus of power tag your target with mage chains and quickly land one shot of Arcane Barrage on the target to land your stun. (Remember Arcane Barrage does great AoE damage so try to hit as large of a crowd as possible with it.) After the stun lands line up an easy Arcanopulse and drop the last two Arcane Barrage on target. If need be by now Arcanopulse will be off cd before your locus of power ends, allowing for the finishing blow to come with extra range and Mpen.


Quick Note:
While it is better to wombo combo with locus of power activated during your whole chain it is likely that as soon as you root yourself the enemy team will register you as a potent threat and come for you. Do not be afraid to disengage locus of power early if it means you will survive the fight long enough to get some kills. In fact there are times when I only get off my stun then find myself breaking out of locus of power for the bonus movement speed to reposition myself.

Start the game off with a trusty Doran's Ring Health AP and mana regen? Yes this will do fine for the early game. After I get boots I usually stack another ring. These things are the cheapest items for the stats they give and can really carry you through the early game.

Sorcerer's Shoes The only boots for a burst caster (ok if u pick up Mpen elsewhere lucidity will work better)

Rylai's Crystal Scepter Our first big purchase. Now this bad boy is going to give you everything you need at this point. Other Char's are starting to throw their weight around a little bit so the extra health will stave you off. The AP bonus is enough to keep up the burst. Then the main attraction, the brutal slow that Rylai's gives. As a burst caster who is rooting himself in place in order to use his combo I can't imagine a better item to get. Rylai's will cause any opponent without multiple blink abilities to escape your wombo combo now.

Rabadon's Deathcap So now that your opponents are stuck within your combo it's time to start making that combo hit like a truck. Rab's cap will give you a godlike AP boost and the damage output increase will be duly noted by your opponents.

Morello's Evil Tome Now that your hitting like a truck it's time to start going through your combo like a gatling gun. Morello's will give you this ability. More AP to scale with the ever increasing strength of your opponents. Cool down reduction to get those spells on rapid fire for team fights and the mana regen to pick up the slack of the increased spamability of your abilities.

Now this is the point in the game where everything is dependent upon your situation. Are your opponents cowering in fear of you stacking MR, continue to punish them with a Void Staff.
Are you having trouble with an enemy caster but can't allow your own dps to fall off, grab an Abyssal Mask.
Are you being focused down as you should be? Are you facing overwhelming physical damage? Pick up Zhonya's Hourglass.
Are you facing a pesky veig or Le Blanc that has a bigger wombo than you do? Show him who's boss with a Banshee's Veil.

You are the AP carry, you are one of the dps juggernaughts of your team and therefore you need to know how to do this job effectively or else your team won't pack enough punch to take out the enemy. Now it is not your job to initiate team fights but when you think you can pop a q off into their mix without getting caught go for it, damage is damage take what you can get to have team fights in your advantage. Once the team fight starts make sure that the enemy dps-ers aren't tearing you apart, your tank and support should be capable of this but if one of them slips by lock them up first. If not go for the carry closest to you. Burst them down first with your combo but make sure that your ult is hitting as many people as possible in the process. The damgage will help your team no doubt and the slows you're capping off thanks to Rylai's can disrupt the enemy and/or cause the enemy to be unable to run. Always remember who to focus. The higher the enemy's damage potential the higher on the chain they should be to attack. A half or even one-third health tank does not take priority over a full health carry. If you can kill the carries before they kill your mates not only will you end up getting more kills but you will win as well.

Xerath is a very strong champion and his true strength is waiting to be unleashed on the fields of justice. I hope my guide has been helpful and informative. Thank you for reading and please comment and vote.