Hello, I am here to give you a build I recently made for Skarner, and it totally kicked *** when i tried it the first time, I am not a pro, so feel free to criticize in comments, any note would be appreciated.
I will explain to you only about few things, since I do not know how to explain about the others.
you will see that with this build Skarner is quite a pusher.

though I will not explain about many other things in this guide, I will explain about some things, including the spells.
Ignite: I take Ignite so when my enemy escapes with low health I can kill him any way, or take his health down even lower and other teammate can catch him. feel free to take Exhaust instead.
Teleport: I Take Teleport to get to my lane(or other lanes, if needed) and save if the turret is about to fall, or to push him.

As you can see, I do not max any skill very early, this due to the simple fact, that I do not think it is needed.
feel free to take the skills in what order you want, I just know that this works for me.

Feel free to take any rune you want, as long as it is a greater mark/Glyph/seal/quintessence.
just make sure some are of Armor and some of Attack Speed.

This is one of the things I do not know how to explain to you why I take them, I just know it works.

as you might notice, there are 8 items on the list, so what you need to do is just, when you get to 6 Items, sell the philosopher stone,and buy infinty edge
After that, feel free sell your berserkers greaves and buy the another item, better a damage item, but you can buy an item of defense, if thats what floats your boat. trust me, you will be strong enough so they won't escape from you once you get to them.