Everyone builds SKARNER as a tank but in actual reality, you really don't have to. Before the recent patch on the 18th of October, I found this build to work even without the buff. The buff of his abilities made him even more over-powered then he actually was(especially in Dominion). He is not a easy champ by any means to play. Mastering his moves is key to his success.

Pros
* Great lane survivability
* Deals a lot of damage early game with this build.
* This build allows him to solo if need be.
* His ultimate can be used to you're advantage.
* He has massive life steal.
Cons
* Skarner is not a initiator.
* This build makes him get focused a lot.
* He thinks there are a lot of purple and blue scorpions like him.
* He is extremely hard to master.
* He gets a lot of assists.

Okay. You're going to be like "WTF?" to his masteries but they are what make him be able to be that over-powered champion. This makes him tank-like but yet mage at the same time. He gets massive health and mana regen with also being able to sustain deep threat attacks. Without this tree, Skarner is extremely squishy.

Energize(Innate/Passive): Using auto attacks against champions lowers the cooldowns of Skarner's abilities by 1 second and by 0.5 seconds when used against non-champion units. Auto attacks on towers won't reduce cooldowns at all.
*NOTE* He has one of the best passives in League Of Legends, so when in lane with your teammates, auto attacks from them will reduce the time of your abilities also not just himself.

Crystal Slash(Active): Skarner lashes out, dealing physical damage to all enemies in a small area around him. He charges himself with Crystal Energy for 5 seconds if a unit is struck. If he casts Crystal Slash again while empowered by Crystal Energy, the ability deals bonus magic damage and slows all targets hit for 2 seconds. Cooldown: 3.5 seconds/Radius of AoE: 350/Cost: 15 mana Physical Damage: 25 / 40 / 55 / 70 / 85 (+0.8 per bonus attack damage)Magic Damage: 24 / 36 / 48 / 60 / 72 (+0.4 per ability power)Slow: 25 / 30 / 35 / 40 / 45 %*NOTE* Maxing this out first is key. This is your bread and butter because not only do you get life steal from this ability, but you also deal massive damage too. When you impale, this is a huge move to combo with so spam it. It is also the quickest cool down out of all your abilities.
Crystalline Exoskeleton(Active): Skarner receives a shield for up to 6 seconds. While the shield is still active his movement speed and attack speed are boosted. Cost: 60 mana/Cooldown: 14 seconds/ Shield Strength: 70 / 115 / 160 / 205 / 250 (+0.6 per ability power)/ Attack Speed Boost: 30 / 35 / 40 / 45 / 50 %/ Movement Speed/ Boost: 15 / 17 / 19 / 21 / 23 % *NOTE* This ability is really nice to have. Adds more to the tank like aspect, while also giving you movement speed and attack speed at the same time. I've been saved countless of times because of this ability but its not a ability I would choose to max out until last just because your other abilities are more important.
Fracture(Active): Skarner summons a blast of crystalline energy in a line which deals magic damage to enemies struck and marks them for 6 seconds. If any marked targets receive further damage from Skarner, or if they die when struck by Fracture, Skarner will consume the mark to heal himself. Subsequent marks consumed and unit kills will heal for 50% of the last. Cooldown: 10 seconds/Range: 600/Missile Speed: 1800 Cost: 50 / 55 / 60 / 65 / 70 mana/ Magic Damage: 80 / 120 / 160 / 200 / 240 (+0.7 per ability power)/ Heal: 30 / 45 / 60 / 75 / 90 (+0.3 per ability power)*NOTE* Personally, (in my opinion of course) that this ability needs a little bit more longer range. Some may or may not agree with me on this but mastering this will help you succeed with Skarner. This combo'd with Crystal Slash is you're bread and butter.
Impale (Active): Skarner suppresses an enemy champion for 1.75 seconds and deals magic damage to it. During this time, Skarner can move freely and will drag his victim around with him. When the effect ends, Skarner's target will be dealt the same amount of magic damage again. Range 350 Cooldown: 110 / 100 / 90 seconds/Cost: 100 / 125 / 150 mana/Magic Damage: 100 / 150 / 200 (+0.5 per ability power)*NOTE*Mastering how and when to use this ability is key to the combo of success. This either can almost guarantee you the kill in your combo, or it can also gives your teammates the assists to help get the kill. Using this ability, under towers or in Dominion to have the towers hit them while suppressed, which is also what makes this ability so great. Overall, I think this is one of the best abilities whether it be in team fights or one vs one having Skarner use this ability when he can helps greatly to a team's success. Tips: 1.If used, it can pull a champion through the wall! 2. Do not use it on Master Yi if he is highlandering! It will not stop him and it will cancel your ultimate!

Primary(My Choice)

Ghost- Your Champion ignores unit collision and moves 27% faster for 10 seconds. Cooldown: 210*NOTE* I like this summoner skill because with Skarner and his Crystalline Exoskeleton makes you be able to chase and catch the opponent you're after. It also has a less cooldown then flash. Using this while chasing down a opponent and using Crystal Slashwill slow them down allowing either you or your team to get the kill. Don't get me wrong, flash is one of the best summoner abilities but I've found that Ghost with Skarner is a lot more useful.

Exhaust-Reduces a target's Attack Damage by 70%, Ability/Item damage by 35% and slows its Movement Speed by 40% for 3 seconds. Cooldown: 210 *NOTE* Ghost with this and Crystal Slash you will find to be very useful in the success of killing your opponents. Not only that, but it also helps teammates around you too.

Greater Mark of Insight - Gives 0.95 Magic Penetration - *NOTE* Magic Penetration is a huge factor in Skarner's success. Without it, you won't survive. I use 9 of them which gives you 8.55 Magic Penetration which may not seem like a lot early game but hit a champion in the beginning of the game with Fracture and you will see what a difference it really makes.
Greater Seal Of Potency - Gives 0.59 Ability Power - *NOTE* I choose this over mana runes because with the skill tree, it gives you a lot of mana regeneration already so why not be able to hang with the big boys and use his abilities to your advantage. With 9 of these, the 9 glyphs, and the 3 quintessence runes they allow you to start off without any items 29.07 ability power!
Greater Glyph Of Potency - Gives 0.99 Ability Power - *NOTE* See Greater Seal Of Potency for reason why I choose this!
Quintessence Of Potency - Gives 4.95 Ability Power

ALSO you may try:
Quintessence of Insight - Gives 1.89 Magic Penetration - *NOTE* This is for the extra Magic Penetration if you really want it!

I will put up games played to show his play style in all game types. If you use my build, I want to see how you do and I'm always open up to opinions! Skarner as I said is not an easy champion by any means but if you get the hang of him, he is one of the funnest and best champions available on the market! Thank you for taking your time to read this and I hope you learn a lot from this! - ECLIPSE1221