Skarner is a good champion and i think you should try him when he is free if you don't have 6300 ip or you are not sure if you want to buy him.

Start with sapphire crystal and 2 health potions. Then first trip back buy a blasting wand or ruby crystal. I buy blasting wand first only if i have enough money. After buying one of those items buy 2 or one more health potions. The first items i like to finish first are Mercury's thread or rod of ages. If you are going with mercury's threads first then buy a boot and null-magic mantle after the 3 starter items. If you choose rod of ages first then be more careful since you have less magic resist. When you have finish the two starter items buy a haunting guise or madreds's bloodrazor. Note: i like to buy one or two health potions every tip back. Now you that you have a good amount of health and defense buy a more magic resist. I like to buy Abyssal scepter since it has it has abilities power and magic resit what you need and to top it off it helps your team by reducing the enemies magic resist. My last and final build is a void staff. Most times you don't get to build void staff since game's already over.

I like to get my e first since it's my long range attack until i reach level 6 with my ultimate. I get my q second if i am winning lane early on. If i am losing early on i get w and then q. The combo i do is e w q then r then repeat and you win that is unless they flash or you get ganked out of nowhere. After the e i like to follow up with w then q so i can heal up without losing more health before i heal since w gives me a shield. Q is based on attack damage so you could heal from your e. This is good because if you hit like 5 minions and follow up with q you get health from all of them without hitting them one by one.

I'm just going to leave this blank since I'm not lv 30

Just pray you are not the first targeted XD

Use your ultimate and hope that your team follows up and react fast when you do because if they don't react fast enough you might die first since if you started in the team fight. I like to exhaust the carry and use ult on the champ with most ap damage.

I like to have exhaust and flash. I sometimes like to ult and exhaust at the same time and follow up with my q to slow them down. Flash is just so you could escape or catch up to a fleeing champion.

You should try this build on custom then coop then normal. If you don't get past co-op or normal then plz don't play rank and blame this build since i never even played a ranked game before and only have 7 normal wins as a lv 17/ i don't play normal a lot only co-op and customs. This is my first guide so I'm not sure if my information are correct in the chapters and I'm level 17 so you finish the masteries and runes of your liking. I'm new to this so i don't know how to add pictures to chapters unless you can't add pictures to chapters. The account i play with skarner is Renekaton.