Hey all, this is my first guide and after playing Skarner constantly the past 2 days I feel that writing a guide would be a helpful idea. I base him around a hybrid idea, similar to some popular Ezreal builds in the concept of balancing AP and AD while keeping Attack Speed formidable.

Pros:

Nice Damage output
Compliments any champ with a stun in lane.
Ultimate has endless number of uses
Passive lets you almost spam all his abilities
Fun to play!

Cons:
Relatively Squishy
Stands out and will be targeted in team fights
Mana intensive
not a whole lot of range/has some difficulty with purely ranged Champs (ASHE!)

overall he is a very solid champion and worth a shot.

Because of the hybrid nature of Skarner runes are really a personal preference.

I go with Armor Pen marks to up his early game threat a little, while taking dodge seals to increase the survivability a little and compliment my mastery.

My largest problem with Skarner is how mana intensive he is, so i use flat mana regen glyphs to make early game not such a nuisance, if you still have trouble I suggest picking up Clarity and dropping one of the escape summoner spells.

I go almost purely defense for his mastery, I feel the extra survivability is exactly what Skarner needs being up close and personal with enemy champions. Nimbleness along with the dodge talents compliment my runes and with often give him more movement speed, which is exactly what he can use at times to close the gap, or escape, depending on the situation.

Summoner Spells are purely preference on Skarner, I just find that his shield is the only thing really usable as an escape mechanic so I use ghost and flash to help with that.

Seeing how all of his abilities scale of AP I fill his item build with a lot of Hybrid items, while giving him Ability Power also giving Damage and attack speed.

Guinsoo's and Trinity force are made for this character and I consider the core to this build while the Gunblade can arguably be considered core as well. The lifesteal also contributes tremendously to his survivability mid-late game. Instead of a gunblade when a game isnt going so well and money is tight I will purchase a Wit's End for some cheap damage output and magic resist.

I add defensive items towards the end because that's when the most damage is going to be put out and hell need to survive. I use a sunfire cape to help with the health pool as well as some damage output, the Sunfire cape actually makes it so you don't have to hit enemies you use Fracture on because any damage done to them will heal you. Rylais is an optional end item, a Banshees Veil or most other defensive items will fit the bill, I just prefer utility alongside giving Skarner some buffed up health.

I feel going purely AD gives his shield less worth and makes Fracture almost worthless. Going pure AP would worth but his auto attack is less of a threat. I feel a hybrid not only balances this but makes his damage output significantly greater.

The first few games I played with Skarner i was maxing Crystal Slash and then his shield while waiting until the very end for Fracture.
While the shield is good, the damage output and heals provided by maxing Fracture second outweigh the attack/move speed that you get instead of just keeping it rank 1. And by the time you are at end game it should be maxed out anyways.

Crystal Slash is his bread and butter, and literally every stat you get with your items will benefit this move, it scales with AP,AD and speed by lowering the cooldown to almost nothing.

EARLY GAME.
I almost always lane bot with a buddy who is playing Wu Kong recently there is little to no cc so I am most often the initiator of early game fights.
Poke with Fracture, while farming last hits with Crystal Slash on creep. Play defensively will harassing and keeping them at a distance until level 6. Once you get impale let your partner know when and go for the squishiest champ in your lane. 99% of the time it'll end in a kill.

MID GAME.
Go where needed, remember to continue to farm creep throughout the game, but after the lane phase ends I play Skarn a lot like a jungler while still protecting my original lane and helping in skirmishes, try to keep the blue buff on yourself as often as possible, seeing as mana becomes a problem. Remember his item build is extremely expensive so farm creep as much as possible.

LATE GAME.
Stick with your team, nothing is 1v1 anymore. Which is where I think Skarner shines. Stick near your tank and impale the carry as soon as you can during team fights, if your team is smart they would be focusing that champ anyways. Spam crystal slash and Fracture to not only heal yourself but put out some nice damage to the entire team.

Skarner is an awesome champ, that over the course of 2 days since his release has become one of my favorite characters to play. Play it smart and there should be almost no reason to die in a game.

Thanks for reading, like i said its my firs guide so take it easy on me. Comments and constructive criticism would be much appreciated.