Hey guys, as the eu servers are down again, i'm giving you this guide to my main Jarvan, the exemplar of Demacia. I mostly play him solo top lane and build tanky items, but his damage is still pretty viable overall.
Playing experience:
Dont know how much normal games i played with him.
Ranked games: 15

There are a lot of options to start with.
If u know, you are gonna face some AD bruiser, you definetely want some extra armor.
Start with a Doran's Shield, the extra health regen is good aswell.
If u want to be super aggressive start with Doran's blade. The lifesteal will help u to stay on lane, and the extra damage is nice 2.
Normally you start with a regrowth pendant and a health pot, cause u wanna stay in lane.
On your first way back, get your Philo stone and either your Boots of speed, or if u have enough money, your Mercury's Treads.
The first major item you are aiming at is Trinity Force. It gives u nearly everything u need and u will be tanky enough, since you get this at level 10-12 if you farmed well.
Afterwards you gonna build resistences to counter their carries.
If their team is mostly magic damage, you should go for Banshee's Veil. It's also good to counter some stun or burst, which will hit you while initiating.
If their team is mostly physical damage, build a sunfire cape. Since you are the one staying in fights the longest time, it will also give you some extra damage output.
As u will have 150+ resistances on each, armor and magic resist, you want to build some further damage. Best item to go for is Atma's Impaler cause u got a bunch of HP now.
If the game isnt over at this point, you can choose your last item. Some good options are Guardian Angel (oh you are even more unkillable now), Force of Nature (cause health regen is always nice) or even some damage item like Bloodthirster or even an Infinity Edge.

If u going solo top there are 2 options and playstyles, which i recommend.
1. You are facing another bruiser (Lanewick, Irelia, Singed, etc.)
Play defensive versus those. Concentrate on farming and lasthitting. Hardest opponent as Jarvan will be a good Lanewick cause he will just heal up from any harass u do to him and can harass you quite good aswell. Wait for your junglers to gank and safe your ult and some mana for those ganks.
2. You are facing a mage / AP caster
Play offensive versus those. You can easily deny their harass in early levels cause of your flat magic resist from runes and your damage isn't that bad to be honest. The only champs you could have problems with are Rumble, Malzahar, Mordekaiser and AP Alistar, cause they are all quite tanky (Malzahar only late levels) and will heal up or just tank your harass with their shields. Just do like you would do versus bruisers, which means farm farm farm.

You will be the main initiator of your team, unless you have something like an Amumu in jungle.
Just do your flag-toss combo in, shield yourself, ult their squishie carries and wait till your damage dealers finished them off. Important point due to teamwork is your teleport, cause you can get to dragons, barons or teamfights easily and pretty unexpected (if your team places wards in bushes)

Why flash and teleport?
Flash: cause it's simply the best escape spell for any char and can be used for initiation aswell. (Ghost is viable and not bad at all tho.)
Teleport: As you are laning top lane u will be the guy most far away from your team and dragon.
Teleport is just a easier way to get there and also a good ganking option.
If you need to base, cause u got harassed too hard, you can teleport back to your lane again and u won't loose much creeps or tower.

Other good options:
Exhaust: If u want something to handle your opponent better or another way to give you a kill.
Ignite: Will be a good option vs bruisers, which can heal up fast from their almost secure death ( Warwick's Q, Irelia ult, ...)

Quite easy cause u got 2 spells with a nice range.