At this moment is one of the best melee fighters in the game. He has just insane passive which combined with AS runes gives him ability to spam and out damage almost anyone in 1vs1. In addition of that he has shield which absorbs nice amount of dmg and heal which makes him powerful unit in the field .

Pros
1.Great Damage
2.Has shield, heal and slow
3.Can stun and drag enemy from battle
4.Has very good survival
5.Low CD for skills

Cons
1.Has a very low range for ulti and Q skill
2.Hard to creep at low lvl
3.Greatly depends on Farm/kills

For masteries I take 21 points on offense by taking attack speed ,which scales nice with passive ,and because all of your skills does some dmg in magic its important to take 15% magic penetration as 4% magic and physical dmg.
in utility I take Haste which improves my ghost , its always good to have more speed, and greed because 1 gold is better than nothing. You can also change greed by putting mastery in Utility Mastery

Greater Mark of Attack Speedx9
Greater Seal of Replenishmentx9
Greater Glyph of Attack Speedx9
Greater Quintessence of Desolationx3
Greater Quintessence of Healthx3
I use red and blue attack speed runes because of skarner passive energize which allows me to spam Q skill more often or survive on 1vs1 with more shield on me.
Yellow runes gives me nice mana regen in early game which helps harass in lane or just stay longer in lane.
For Quintessence I use Armor penetration runes as for a melee fighter it very helps for kills in early or late game ,If you find hard to live in lane than go for health runes.

I start with Long Sword and Health Potionon Skarner ,as you can creep easier and helps for FB.

When you first go back buy Sheen or ,if you have hard life in lane go for Bootsand Ruby Crystal. Try to go as fast as you can for Trinity Force , because it gives you nice dmg, slow combined with Q skill and speed from shield they can never run out of you.

After you got Trinity Force go for Pickaxe or if you have lots of money go for Guinsoo's Rageblade. With your attack speed and fast reuse of skills it's very easy to have max 8 stacks of it. If the game still goes on go for Hextech Gunblade.
For final items you can choose go for Black Cleaver and Madred's Bloodrazor or some survival items like Guardian Angel.

energize




Your first skill to max is Shattered Earth. This skill has so low cd and combined with AS and energize it looks like it has no cd at all. When you reach 2nd LvL take Seismic Bastion , shield + attack speed + movement speed is just too good to be true so you max this skill after Q. The last skill you max is Ixtal's Impact, because this skill is pure AP scaling its not very good as AS hybrid Skarner. Take one point of Ixtal's Impactat LvL 4 for some heal and dmg.
Your ultimate is Impale. This skill is pure AP scaling but its great ultimate to take out and drag enemy champions out of the fight or not let them escape from you. If you combine your Ghost + Seismic Bastion with Impale you can drag enemy quite far away.

Skarner Has a good aoe Q skill which helps farm fast and easy but has very low range. Because of this low range the biggest enemy for you is all ranged class. If there is an option for you not to be in lane with enemy ranger than don't be in that lane.
Skarner highly depends on farm/kills it is the best thing if you go solo against any melee opponent except Blitzcrank,because of grab or go double lane with anyone who leaves you creeps.

For summoner spells I take and because its great spells to run away , catch an enemy or just flash + ultimate an enemy and drag them away from team or fights.

Skarner is one of the best melee fighters out there. In early game you can slow champions and help to get fast FB .With your Seismic Bastion you can easily gank in other lanes , and with ultimate you annoy enemy team by disabling there healer or high dps .So if you want a good dps ganker ,which has good survival and dmg, Skarner is the best choice at this moment.