Skarner is a really good carry in my opinion. All the games i played with him, as long as my teammates weren't terrible I usually do pretty well either in Hero kills or assists. His crystal slash is an amazing AoE that destroys team fights.

My reason for adding in the Rylai's last is cause it's one of those situational items. If you're having problems getting people slowed down you can get it earlier I usually don't get it. The other items are relatively obvious as to why you get them. You might question the archangel's but I don't use a mana rune page on him of any sort, as well as it's more AP.

Well, sort of obvious this is an ap build for him. Attack speed relatively means nothing for this build you would actually probably want more CDR than what I get but what I have works for me. Whatever works for you, you can use.

The summoner spells are whatever you want again these work for me. Whatever works for you.

Pros
Excellent chaser even with lvl 1 shield.
Large amount of AoE damage from crystal slash
Constant heals

Cons
Low level shield means more vulnerability.
Low amount of normal damage from basic attacks.

You ordinarily want to go with a stun of some sort. Fears work too. If you have a lane fiddle that is excellent. Things that worked for me with a lane fiddle was waiting for an enemy champion to come up to you while fiddle is hiding somewhere have him ult and you ult at the same time and the champion is basically screwed since he's going to fear immediately after your ult breaks. Just Q and E to death. Rinse and repeat.

He's one of the most enjoyable new characters i've played in awhile.