Introduction
Hey guys, this is my third guide, but hopefully my best. My old builds were focused on glass cannonesque gameplay, which can work BUT really shouldn't be used in ranked play, it leaves too much up to your team.
CHANGE LOG: My 
Swain guide has recently been completely remade, please go check it out. It contains a large amount of information and you may find it useful.
Thusly I am writing this guide about 
Skarner, a champion I personally think fits in really well to any team and can definently be a solid part of a ranked team, why will be discussed below.
He is a fairly quick jungler, and doesn't rely on 
Wriggle's Lantern, which has benefits and drawbacks, these will be discussed below too, along with my reasoning for neglecting to purchase it.
Runes
For runes, I take 
Greater Mark of Attack Speed, 
Greater Seal of Armor, 
Greater Glyph of Scaling Magic Resist and 
Greater Quintessence of Movement Speed.
My reasoning for these is fairly standard:
The marks enable faster jungle, and I choose these over 
Greater Mark of Attack Damage and Greater Mark of Desolation simply because they synergise really well with Skarner's passive, 
Energize.
The seals give armour, which mitigates damage from minions allowing for safer jungle and thusly faster ganks, need I say more? 
Greater Seal of Health is a decent choice too, I just prefer the armour option.
The glyphs i choose because minions in the jungle don't deal magic damage, and us such you don't need magic resist early, but these do provide some survivability in later team fights and even when ganking, thusly I like these runes.
The quintessences are, in my mind, irreplacable. Skarner, especially with red buff has some nice CC in red buff and 
Crystal Slash, even pre-6. You can use your 
Crystalline Exoskeleton on top of your Greater Quintessence of Movement Speed and the masteries you chose to keep up with any runners and constantly apply slows.
They will need to use 
Flash, 
Ghost or abilities to escape as running they will not be able to escape you, and if none of these are options, you can easily kill, especially with help from team.
Masteries
For masteries, I max out the defensive tree as I play as an offtank with strong CC and some damage, and this allows me to tank more damage whilst surviving longer and applying more CC.
I make sure to maximise armour/health and minimise damage taken from all sources and specific minion damage to, once more, permit an easier jungle and survivability in team fights.
2 masteries that don't relate to these that I choose will be detailed below:
Initiator
: I choose this because it is the very NAMESAKE of what you are, at the start of the team fight you will (SHOULD) be above the 70% health threshold, meaning it is in effect. It makes you faster, thus allowin you to capture someone with 
Impale and drag their defenseless, motionless, crystallized body into your team. This is countered by 
Quicksilver Sash, so be careful and always Impale the person that your team needs dead first, most likely an AD carry such as 
Ezreal or 
Graves.
Summoner's Resolve
: I grab this spell to enhance the effectiveness of 
Smite. Alot of you may question this, as I could recieve less damage from AoE abilities, gain health regen for an easier jungle or just get a bit more magic resist.
I agree, but that been said, you should be smiting often to make your jungle faster, especially on buffs, dragon and baron. Thusly you gain 10 extra gold per use of Smite, which can add up to 10 free gold per minute. In 20 minutes, you'll recieve around 180 free gold on top of your already gained gold. This amount isn't huge, but it also isn't insurmountable, and I would far rather get 200 free gold than have 2 magic resist.
This is personal and change it if you disagree with me, but I think the added gold is a nice bonus.
I take the utility tree for a few reasons:
1)
Summoner's Insight
: This enables you to Flash 15 seconds earlier than otherwise, which is nice for your engagement.
2)
Expanded Mind
: This gives you an expanded mana pool, allowing you to spam spells more often and allows you to give your blue buffs (excluding the first) to your mid lane, this will help them immensely and they will be happy that you are a team player. With this additional mana and 
Philosopher's Stone, you will be able to sustain your mana enough without relying on blue buff.
3)
Swiftness
: This speeds you up more, synergising with your Greater Quintessence of Movement Speed and
Initiator
mastery, allowing you to easily catch opponents and Impale them.
4)
Runic Affinity
: I don't think I really need to explain why, but blue buff for longer enables faster and safer jungle, red buff gives more opportunity to gank and having baron for an extra minute, assuming you don't die, is very handy.
Items
Starting with 
Regrowth Pendant and a 
Health Potion is what I recommend. With your Crystalline Exoskeleton and 
Fracture, you can sustain most of the damage and get Red buff whilst still having around 70% life, thus giving you your movement buff. You can then gank with red buff and Crystal Slash for CC, while you move very fast.
You can then upgrade your Regrowth Pendant into a Philosopher's Stone, grab 
Boots of Speed, build to a 
Heart of Gold and upgrade your boots to either 
Ninja Tabi or 
Mercury's Treads, depending on the opposition team.
But this is called the Offtank Anticarry, and with this you gain a little health, but no real resistances and you don't qualify as an offtank just yet. Oh, no... its time to tank up.
This is where the build becomes a bit more ambiguous, because obviously it will depend on the enemy team.
If the enemy team is stacked of AP with alot of burst mages or constant mages, 
Banshee's Veil isn't a great choice, as such I would choose 
Force of Nature and follow up with some kind of health, such as Warmog's Armour. Against a stacked AD team, Warmog's Armour or 
Sunfire Cape and 
Thornmail would be a good choice.
Against a standard 'meta' team, I would go with the build detailed above in the item purchase section. Sunfire Cape provides good health and armour, and also topped off with some nice AoE DoT, which is nice as you are likely to be rushing into the enemies and applying it to everyone.
Trinity Force is a best of both worlds kind of item. I wouldn't rush it, as you need to tank up a bit first with the Sunfire Cape, but trinity force adds nearly every stat possible. It makes you tanker, stronger, faster and gives you two very nice passives, one that can slow an enemy, stacking with Crystal Slash and another that adds nice damage to your next attack every time you use an ability, and you can spam your Crystal Slash to keep procing this, thusly Trinity Force is a very nice item for Skarner.
After this, you have decent health and armour, but are lacking a bit in magic resistance. Due to your health and regeneration, Force of Nature is a great choice, but as you will be initiating and facetanking the enemy team, they might try to apply CC to you before you can Impale their carry, and thusly I value the passive from Banshee's Veil highly, it also offers some health and mana, aswell as magic resistance, making you more tank.
After completing these items you are able to tank most fights fairly well, especially if you Impale their carry and you're team collapses onto them, as they will have lacking damage, and as such you should now focus on improving your ability to do this aforementioned task, instead of tanking up more.
To accomplish this, I see 2 main items: 
Youmuu's Ghostblade and 
Shurelya's Reverie, but I prefer the latter, especially when you already have Philosopher's Stone.
After this, you have speed, tankiness and CC, but I decide to improve the CC and tankiness by upgrading the Heart of Gold into a 
Randuin's Omen, so when you dive their team with your Shurelya's Reverie and Crystalline Exoskeleton, as you Impale the enemy carry, you can activate your Randuin's Omen to slow the whole team and mitigate their damage.
After this, you can change the build as neccessary and purchase elixers to further increases your damage and tankiness.
The Wriggles Dilemma
You might ask, Jayzorz, why not buy Wriggle's Lantern? You may even state some reason's why Wriggle's Lantern may be good, such as the attack speed from Greater Mark of Attack Speed and Crystalline Exoskeleton can make Wriggle's Lantern's passive proc often and as such allow very fast jungle clear times, and make killing dragon and baron very fast too.
I agree completely, but I personally feel that Skarner is already a fast enough jungler, and the gold aswell as tankiness offered by Philosopher's Stone and Heart of Gold is too good to resist, and I personally don't like getting Wriggle's Lantern after these as it is quite late and past its prime usefulness. The same can be said about the GP5 items, getting these late defeats the purpose of their passive, thusly I choose to get these instead of Wriggle's Lantern.
This aforementioned fact elaborated, I also do upgrade Philosopher's Stone and Heart of Gold to Shurelya's Reverie and Randuin's Omen respectively, and both of these items are great for Skarner, whereas Wriggle's Lantern would be sold off later.
Summoner Spells
As any jungler should, I take Smite. It can secure buffs, dragon and baron, unlike any possible replacements, and as such is a MUST HAVE, especially in ranked play. Do not mistake 
Ignite for a replacement, as it doesn't work.
The other spell is more related to personal preferrence, but I have to say I think Flash is the best choice, it is useful for running away or escaping from potentially sticky situations, but even moreso for a Flash Impale combo. TOO STRONK.
Ghost is a decent alternative to Flash, but I think that Flash Impale is too strong to give up. Once you complete Shurelya's Reverie you have enough speed and the ability to Flash.
Exhaust does increase your gank potency and can give lanes a hard time, it can also be used on the carry so you can catch them and Impale. I personally prefer Flash, but would choose exhaust if my team did not take an Exhaust.
Ignite is only good on a pure ganking champion such as 
Shaco, but I personally do not even like it on him. I think that Smite is to valueable to pass up and Ignite limits your escape and lategame.
Anything else, don't even look at.
Ranked Play
Skarner is a great choice for ranked play. He can clear the jungle quite fast, his ultimate can win games and he is a potent ganker, not by himself but with teammates. Especially at level 6, he can drag running foes back into your team where they can apply some more CC, you can slow them and force them to try and run again, even after they flash in some cases.
Jungling- How to start
At the start, begin at the Ancient Golem with Crystal Slash. After killing it, you will become level 2, level up Crystalline Exoskeleton as it allows you speed and safety in the jungle. Follow a standard path from here, that is wolves > wraiths > double golems. You will now be level 3, I suggest getting Fracture and finish off your route with the red buff.
Team Work
Effectively you have to absorb the damage for your team and initiate straight in with Shurelya's Reverie and possibly Flash to Impale the enemy carry. After you drag their carry into your team and he dies, it becomes a favoured fight. Continue to spam your abilities, focus their damage dealers and try to zone them from the fight. Without damage, the enemy team will be useless and your team will surely win the fight.
Summary
To summarise, starting with GP5 will enable you to attempt ganks whilst still gaining money for lategame efficiency and you're mission is to take damage and enable your team to kill the opponent's carry, thusly giving your team the advantage.
Occasionally this may be inglorified as you aren't may not get any kills and you might also die whilst tanking for your team, but you are contributing to your team immensely if the carry dies thanks to your ultimate.
Thank you for reading, test out my suggestions and build and have some fun.
As a sidenote, I have pictures to upload, but will do this at a later date. Ask me any questions you want, post suggestions and constructive criticisms, but please don't just flame or downvote without saying why. I aim to improve this guide on people's information to enable everyone the best information attainable. Bye guys.
Build Guide
Discussion (2)
Kennen to stunlock his foe and leave them unable to do anything.
Nunu, where 
Absolute Zero.
