This is my First build I've ever made, so bear with me. :P But since i love Skarner so much i though i have to figure out a really good build with him, and when i found a pretty good one, i decided ill share it with everyone else and see what they think, so here it is.

Skarner I believe is a pretty Balanced champion at this point. He is also really fun, best part id have to say is his Ultimate, i just get the best feeling inside when i drag someone into my turret or right into my team. Btw best thing ever to do to ruin a Tryndameres day is when he tower dives you and ults kite him til the last 2 seconds of his ult then ult him and watch him die to the turret :)

So i go with the 9/21/0 build because it makes Skarner able to take a lot of trash and then with the 9 points in Offense he can dish that damage right back out.

These Runes are pretty good for early game, but these are the runes i use for all my AD champs, i dont buy runes too often... so there might be better ones. But from my experience with playing with them they seem to work out pretty well.

I pick Flash and Exhaust. Flash for a quick get away or for a tricky flash ult and drag into your team :) and then i use exhaust for chasing as it works very well with your Q. but if your a fan of Ignite im sure that would be fine fro replacing Exhast.

So this is probable the best build ive made for Skarner so far, but im still working on it though, but dorans right really gives Skarner some more early game power along with mana regen which helps out a lot, when you get your tear of the goddess pretty much all your mana problems are solved, and you want to get that to a manamune as fast as you can so you can start gaining more attack damage cause your next item is gonna be AP based, now i chose to go with Lich Bane over trinity force because i plan on getting a Rylais after that, and that will cause a slow on his abilities, and the Lich bane with give be basiclly twice the amount of damage every 2 seconds. One thing I learned though is to not build attack speed on Skarner, perosnally i think its a waste because you have your W that is a attack speed steriod.

So definitely Crystal slash first, this gives you an amazing farm, along with its double damage on 2nd hit, and its slow its a must get 1st. Second is Exoskeleton because this thing buffs you so much movement speed so you don't need ghost and attack speed boosts so you don't actually need attack speed items. Last i get Fracture because even though the heal is nice and all, the heal isnt for that much and the damage it does for its cooldown, its just better to get Crystal Slash first.

Pros
- good farm
- good damage
- need to think of some more... forgot about this section

Cons
- if targeted can die kinda easily
- need to think of some more...

Just keep it on the safe side and you can use your q to pick up multiple last hits.