Introduction
Hello, I'm dezhawk, playing as jungler for a ranked team called Faroese International Gaming, FIG. Not professional, but it's our goal. Here's a guide about 
Skarner, going deeply into everything, that has with Skarner to do.
Pros & Cons
Pros
Has a perma slow
Fast jungler
Good ganks with ult
Abilities scaling with both AD and AP
LOOKS AWESOME!
Cons
Can have hard early game
Item dependant
Often mana-hungry without blue-buff
Ability information and tricks
Crystal Slash is a point blank area of effect ability that deals physical damage to all nearby enemy units, buffing Skarner with Crystal Energy for 5 seconds if it hits an enemy. While Skarner has Crystal Energy active, Crystal Slash deals bonus magic damage and slows enemy units hit.
Crystal Slash procs spell vamp and 
Rylai's Crystal Scepter's slow similarly with all area of effect spells and abilities with diminished effect.
Crystal Slash pops spell shield.
Crystal Slash will damage 
Black Shield and the slow is negated. Crystal Slash's physical damage will be applied in any case.
Crystal Slash has no cast time and does not interrupt Skarner's previous orders.
Energize reduces Crystal Slash's cooldown to 0.6 seconds when continuously autoattacking champions with max attack speed (2.5 attacks per second) and cooldown reduction (40%).
Crystalline Exoskeleton is a self-target ability that grants Skarner an absorption shield for up to 6 seconds. While the shield is persists, Skarner gains bonus movement speed and attack speed.
Crystalline Exoskeleton has no cast time and does not interrupt Skarner's previous orders.
Crystalline Exoskeleton's bonuses are lost if the shield breaks.
Fracture is a pass-through linear skillshot that fires a wave of energy in the target direction. Enemy units hit take magic damage and are marked for 6 seconds. Damage from Skarner will trigger the mark, causing him to heal for a flat amount. This heal also occurs if Fracture kills units it hits. The heal amount is reduced by a percentage, dependant on both the number of units killed by Fracture's cast and the number of marks triggered.
Fracture procs spell vamp and Rylai's Crystal Scepter's slow similarly with all area of effect spells and abilities with diminished effect.
Fracture pops spell shield.
Fracture will damage Black Shield but units hit are still marked.
Impale is a targeted ability that deals magic damage to a single target enemy champion and suppresses them. While the target is supressed, it will follow Skarner's movements. When the suppress ends, the target takes the same amount of damage again.
Impale procs spell vamp and Rylai's Crystal Scepter's slow similarly with all single target spells and abilities with full effect.
Impale pops spell shield.
Impale will damage Black Shield and the suppress is negated.
While Impale's suppress is active, Skarner cannot autoattack, cast Fracture or use 
Flash.
If Impale's suppress is prevented or cleansed, Skarner may take full action once again.
Cleansing Impale's suppress prevents the secondary damage from being dealt.
Impale can move targets through walls if cast across one, or if a knock-back/pull effect moves Skarner.
Knock-backs and pulls on an Impaled target will move it, but the unit will travel back to Skarner's location.
While Impale's suppress is active Skarner is considered to be facing backwards of his movement. This can affect some abilities' effects such as 
Mocking Shout
Lore
Centuries ago, there lived a race of creatures as ferocious as they were wise. The brackern were unusual beings blessed with the earth's primal magic, embodied in the form of crystals. Their kind knew of an arcane ritual to bind their life's essence to a crystal, communing with the magic embedded in it. With this power, the brackern thrived in the Odyn Valley, protecting both creatures and crystals alike. Despite attacks from those looking to claim the primal magic, it seemed that nothing could get past the brackern's defenses. Nothing, that is, until the devastation of a Rune War.
A vicious battle was fought near the Odyn Valley and the unleashed chaotic magic poisoned the crystals. The brackern began to grow sick and die, and no amount of defensive magic could reverse the effects. To avoid extinction, their only course was to hibernate underground until the wars stopped. The strongest, most intelligent brackern hibernated closer to the surface to awaken first and assess the world's condition for the return of their race. The recent mining operations and violent escalation in Kalamanda were enough to awaken the first of these vanguards. When Skarner burst to the surface, he lashed out in anger and confusion. Reason eventually won out over his anger when he realized that the agents of the League who found him were simply functionaries. Skarner was invited to the Institute of War to share the brackern's story. In return, the summoners told him about the history that his kind had slept through. Much had been done to curb the unchecked use of magic since the Rune Wars, but it was obvious that the world was not yet safe for his kind to reawaken. For now, however, there is a place where Skarner can use his power to change the world into one to which his kind could eventually return: the League of Legends.
"The humans have not yet learned to control their magic - what once was Kalamanda is now a crystal scar on the history of this world." Skarner
Ability Usage
Crystalline Exoskeleton allows Skarner to cross the map faster. With this and Crystal Slash, you can chase enemies by slowing them continuously while staying close.
Fracture's heal is activated from any damage source. Try using the skill on a group of minions and then using Crystal Slash to heal yourself quickly.
Fracture's heal is also activated when Fracture kills the target.
Skarner has great chasing potential, use the speed boost granted by Crystalline Exoskeleton to close in on enemies, then use Impale to drag them back into your team.
Do not be afraid of spamming your abilities as your Energize will reduce your cooldown ability per auto-attack.
Crystal Slash can also be used for presence revealing stealth champions, as it will charge up if it hits a stealthed champion.
Skarner's Impale can be used in a variety of ways. Note, however, that you cannot use Flash during the ultimate. You can use other spells such as 
Ghost or 
Exhaust, however.
Defensively, it can drag in turret diving enemies when they go in for a kill.
When an enemy champion is in your team's fountain, Skarner can drag them into the obelisk for an almost guaranteed kill.
It can be used to pull an enemy away from a fleeing ally, allowing them to escape.
The immobilization can be used to prevent an enemy champion completing a channeled ultimate.
You can use it to separate a key member of the enemy team, particularly the carry, to swiftly kill.
To pull back a runner from a teamfight.
To pull an enemy away from their turret or towards your own.
If you're chasing an enemy try using it to pull them back to your allies.
While using Impale, Skarner is also free to use Crystal Slash and Crystalline Exoskeleton while dragging his enemy.
Using Crystal Slash on a minion, and an auto attack on your target before using Impale will let you use Crystal Slash a second time while Impale is active, and let you proc the extra damage and the slow. Don't forget to cast Crystalline Exoskeleton to get the speed boost.
Build Usage
As Skarner needs to be very close to his target to do damage, any build should look upon survivability items with either health, armor or magic resistance.
A 
Sunfire Cape can be bought to inflict extra damage with Impale, as well as trigger the heal from Fracture.
Skarner's short cooldowns and great scaling with attack speed, attack damage, and ability power make him a perfect candidate for taking advantage of the cost effectiveness of 
Guinsoo's Rageblade.
A 
Trinity Force is an exceptionally strong item for Skarner, 
Sheen gives his ablities more damage and gives him more mana, 
Zeal increases his already strong chasing power by giving movement speed and the attack speed works well with his passive, 
Phage gives more chasing power, damage and provides some extra health.
The Sheen effect can be procced almost every single time due to his passive reducing the cooldowns of his skills and the ability to spam Crystal Slash.
Building 
Nashor's Tooth on Skarner gives him many useful stats. Its combination of large cooldown reduction and attack speed bonuses to proc his passive gives him incredible ability to spam his skills. The mana regeneration helps his naturally low mana regeneration, and the ability power is useful due to his decent AP ratios.
Getting a 
Manamune will help with mana problems, but does not grant much late game utility.
Getting a 
Phantom Dancer or a item that gives Attack Speed will help his passive reduce cooldowns faster.
Getting a 
Philosopher's Stone early will help to sustain mana and health.
It can be built into 
Shurelya's Reverie which helps with initiating fights, catching enemies, or escaping.
Building 
Eleisa's Miracle provides good Mana-Regeneration and allows you to purchase 
Boots of Swiftness without having to abandon Tenacity.
Randuin's Omen is a strong item if the enemy is kiting you, as it slows their movement speed if they attack you.
Hextech Gunblade and 
Bilgewater Cutlass also have great slowing effects that are actives.
Jungling
Start at Wolves, say to you're ap carry, to hit them. Then go blue and ask for a hard leash, 300-400 health. Use 
Smite here. Go towards top or mid if gank is available. If not, go Wraiths, then take Golems, if you low on hp, you can gank mid. Then wait until Smite is up. Go to red, smite it. Remember to finish it with Smite, because maybe that enemy 
Tryndamere is in the brush, waiting until it's low. Gank often to make you're enemy's burn the summoner spells, like Exhaust, Ghost or Flash, when ganking.. Then at lvl 7, counter jungle some, smite the big wraíth, and one auto attack, and let one small wraith after, so you look like a massive troll-face :D
Thanks for reading.
Bye, and thank you for reading my Skarner guide, hope you guys, got something out of this guide, remember that Skarner is more viable as jungler, than solo top. I'll maybe do a solo top guide, but first of all, a bunch of new guides. Send me a message which one you want to have. I can't play so much because of my School.
Build Guide
Discussion (9)
Cloth Armor, 
Health Potion x5 OR 
Regrowth Pendant, 
Quicksilver Sash to end the suppression from 
Alistar, 
Olaf, 
Morgana and 
Gangplank also counter his ultimate.
Singed's 
Fling or 
Headbutt) can help an ally that is dragged by 
