In the ancient civilization of Shurima, the mage called Xerath practiced magic with undying passion. He believed that with enough magical power, he could gaze into the heart of Runeterra to know the secrets of history and the universe beyond. Such magic was beyond the limitations of a mortal body, but Xerath obsessively pursued a path to infinite power nonetheless. With every breakthrough he grew more and more powerful, yet not without consequence. Xerath's increasing arcane abilities wrought havoc on his physical form. Desperate, he undertook a dangerous ritual to transcend his dying body. The outcome would be immortality or self-destruction. Violent magic unleashed during the ritual caused devastation throughout Shurima, but when the dust settled, Xerath emerged as an ascended being of pure arcane energy.
Free of flesh and bone, Xerath held nearly infinite power at his command. However, in the wake of his chaotic ritual, the mages of Shurima feared his careless disregard for life would bring ruin to the kingdom. After a terrible struggle they subdued Xerath, but they could not destroy his ascended form. Instead they trapped him within an enchanted sarcophagus and sealed him in an underground tomb. Eons passed, civilizations rose and fell, and Xerath's imprisonment was lost to memory. For centuries, Xerath's vast power tore away at the sarcophagus and weakened its spell. Finally, he willed forth a burst of magic that shattered his prison, but its core remained, containing Xerath and his power within its broken pieces. Seeking to rid himself of this burden, he was drawn to the magic of Valoran's nexuses and found he could absorb their power. Yet the nexuses had gatekeepers: petty mages known as summoners. Xerath knew his key to true freedom from his prison lay in gaining their trust, and he offered his power to the League of Legends.

“I have no need for vengeance. Time has brought ruin to the mages of Shurima and I alone remain.”
Xerath, the Magus Ascendant

Why Xerath?

I chose Xerath as I wanted to have a great ranged AP that could do a great amount of damage with very low cooldowns. Xerath gives me the ability to out range almost any champion and gives great poking early game. Using Xerath I have found that teamfights are much easier as I can destroy most melee champions that are harmDing my team without getting myself to involved into the fight. Xerath is one of the greatest champions in this game as far as AP mid lane goes. He sometimes fails against good Veigars, as they can stun him and Ulti + Q him for a easy kill end game. Yet if you get to stun him you can do the same to him so it is a back and forth thing.

Pros
Great range
Fast cooldown ulti (36 seconds with 40% cdr)
Tons of damage (its terrible i know)
doesnt need to engage head on into fights.

Cons
Skillshot heavy
Sometimes hard to get in place
Cant proc stun if not good at skill shots
Hard to kill tanky teams

Patch V1.0.0.126


Ascended Form
Ascended Form
(Innate): Xerath receives 15% of his ability power as bonus armor.
Ascended Form is a passive ability that gives Xerath bonus armor that scales on his ability power.
Ability Description Leveling up


Arcanopulse
(Active): Fires a long-range beam of energy in a line after a short delay, dealing magic damage to all targets hit.
Range: 900/1300
Width: 100
Cost: 65 / 70 / 75 / 80 / 85 mana
Damage: 75 / 115 / 155 / 195 / 235 (+0.6 per ability power)

Cooldown: 7 / 6.5 / 6 / 5.5 / 5 seconds

Arcanopulse is a linear instant skillshot. After a 0.75 second casting time Xerath fires a bolt of archaeic energy in the target direction, dealing magic damage to all enemy units hit.
Arcanopulse procs spell vamp and Rylai's slow similarly with any area of effect spells and abilities with diminished effect.
Arcanopulse pops spell shield.
Arcanopulse will damage Black Shield. If an enemy unit hit is marked with Unstable Magic, the mark will be triggered but the stun will be negated.

Locus of Power
Locus of Power
(Active): Xerath anchors himself to the ground he is standing on for up to 8 seconds, increasing the range of all his spells and granting him bonus magic penetration. Upon disabling this ability, Xerath gains 35% movement speed for 2 seconds. He can deactivate the ability at any time after 0.5 seconds of casting it.
No cost
Cooldown: 20 / 16 / 12 / 8 / 4 seconds
Bonus Magic Penetration: 10 / 15 / 20 / 25 / 30%

Locus of Power is a toggled self-target ability. When toggled on, Xerath gains increased casting range on his champion abilities and increased magic penetration, but losing the ability to move. This effect lasts up to 8 seconds, and the ability can be toggled off after 0.5 seconds to end the effect early.
Locus of Power will trigger Tear of the Goddess and gain a charge of it upon its activation. However the second activation which toggles the effect off does not proc this effect. It also triggers Lich Bane.
While Locus of Power is active, fear and charm effects will not cause Xerath to move but will still disable his other actions.
Knock-back effects will still move Xerath.
Cooldown begins only after the ability is deactivated or it's duration ends.

Mage Chains
Mage Chains
(Active): Deals magic damage to an enemy and marks them with Unstable Magic for 3 seconds. The next spell Xerath strikes this enemy with in these 3 seconds will stun them for 1.5 seconds.
Range: 600/1000
Cost: 70 / 75 / 80 / 85 / 90 mana
Cooldown: 12 / 11 / 10 / 9 / 8 seconds

Magic Damage: 70 / 120 / 170 / 220 / 270 (+0.7 per ability power)

Mage Chains is a single target spell that sends a electric charge at a target enemy unit, dealing magic damage on impact and marking them with Unstable Magic for 3 seconds. Unstable Magic is triggered if the unit is hit by one of Xerath's champion abilities, stunning the target for 1.5 seconds.
Mage Chains procs spell vamp and Rylai's slow similarly with any single target spells and abilities with full effect.
Mage Chains pops spell shield.
Mage Chains will damage Black Shield, but the mark's placement is not negated.
The ability that triggers Unstable Magic only needs to hit the target, not damage it. If the damage is prevented through methods such as an absorption shield, the mark is still triggered.


Arcane Barrage
(Active): Calls down a blast of arcane energy, dealing magic damage to all enemies in an area. May be cast another two times, with no cost, within the next 12 seconds before going on cooldown.
Range: 900/1300
Effect radius: 200
Sight radius: 300
Cost: 150 / 180 / 210 mana
Cooldown: 80 / 70 / 60 seconds

Magic Damage Per Cast: 125 / 200 / 275 (+0.6 per ability power)

Maximum Magic Damage: 375 / 600 / 825 (+1.8 per ability power)

Arcane Barrage is a ground targeted area of effect ability that calls down a blast of energy at the target location, dealing magic damage on all enemy units within after 0.35 seconds. Arcane Barrage can be activated within 12 seconds from the last activation for up to 2 additional times before going on cooldown.
Arcane Barrage procs spell vamp and Rylai's slow similarly with any area of effect spells and abilities with diminished effect.
Arcane Barrage will pop spell shield.
Arcane Barrage will damage Black Shield. If an enemy unit hit is marked with Unstable Magic, the mark will be triggered but the stun will be negated.
A 0.35 second cooldown is placed on Arcane Barrage in between each activation.

Starting with Q will allow a massive amount of harass and farming as you can drop several minions/creeps to build up your creepscore (CS) very fast

Getting E right after allows ganks at level 2 to be done with ease and allows you to be able to get a kill fighting someone solo like ryze or another low life caster

Getting Q 3rd gives you more range with it more dmg which in turn gives better harass and farm.

Now you grab W at level 4 as it gives you massive range boost and more damage

Q again at 5 and ulti at 6

using a burst like this
E/W/Q/R/Q you should be able to get a kill. using W after E allows you greater range to proc stun with ulti or Q. you should be able to do a burst very fast with most of yours spells ready again fairly quickly,also if you have to use ulti to clear blue feel free as with 40% cdr it will come back in 36 seconds at rank 3.

Reasoning behind and other useful Summoner Skills.

Flash is very simple. It allows you to get into position, and to escape from fights you would otherwise have died in.

Ignite is to stop life stealers from being that much more op, and to get that last bit of damage early game for a kill.

other useful skills would be

Cleanse allows you to escape if stunned or turn a fight around you would have died in.

Exhaust can slow down the ad carry to do basicly 0 damage and run/attack like he is frozen.

Runes are a big factor in every champ, and part of this game.
The reason I use these runes are for these reasons.

1. It gives early game domination (and face it ranked solo/duo is all about early game)
2. It allows you to be better vs high MR at start of game
3. Using runes that give AP gives a flat base increase to how much you can do early and late.

Marks are a given almost 100% of casters use them
Seals are more for a early game assistance and late game few dmg just incase
Glyphs will give you almost 40% cdr if you get boots and morello's or blue buff (add 1 more cdr for 40%) (please note that the glyphs should be Greater Glyphs of Potency. but for some reason i cannot find them in the rune selector)
Quints give you that early game boost of damage - i have to... it gives Tons of Damage. (im sorry lol)

I have change the full Item build as I feel this is much better for the overall game.

Starting boots and 2 health and 1 mana allows you to beable to cast and survive against bursty champs

getting a Chalice of Harmony lets you have that mana regen power without needed blue buff (mostly for those bad junglers)

finish boots to get the best CDR for this point in the game.

Finish Unholy grail. by doing this you get alot more CDR a insane amount of mana regen and a nice amount of MR to survive those pesky mids :P

buying Deathcap now gives your damage a massive over haul and lets you helop out in team fights alot more than you otherwise could.

this next part is up to how yuou play and what you are up against, the next items can be bought in anyway you please. I just put the way i like grabbing them first.
I will explain what each is used for.

Crystal Scepter is used to slow down those fast champs this combined with your range should almost always secure that kill

Zhonys is your best first against bursters (brand, karth ulti, kat ulti, annie ulti and burst, ect.) itll save your life.

Void staff is used to burn down those tanks and ap counters (galio, morde, ect)

V1 -
Guide first made


V2 -
Edited items
Added Summoner Skill / Changed also
Reworked Item explanation
updated Skill order and explanation


V3 -
Changed a few things
Added some pics
Made more clear, Fixed layout

V4 -
Redid item selection
Changed Item text to give info on items i choose

V1 Notes - Sorry if this is small but its my first guide and I will be updating it more as I play and learn how to face all the champions

V2 notes - things to hope for in next version of guide.
I plan on added a laning phase and a mid/late game phase showing players what to do after and during lanes
adding more items for different teams / need more ap / need more life / ect
making guide more clear
adding a ranked section + screens

V3 notes - next version might have a ranked section, items will be fixed for different team needs, will add game phases.

V4 notes - Not playing AP mid as much this season, trying to get back into it (rocking zyra 37/13/18 ranked solo)

http://leagueoflegends.wikia.com - For Skills Info
http://na.leagueoflegends.com/ - For Lore

Reading Other Guides just to see what people think of Xerath and how they play him.