Hello, welcome to my first guide!
This guide explain, how to play a succesfull Jarvan IV.
It's a Tanky/Dps build, so he can deals a lot of damage and also take some dmg.
Pls leave constructive feedback and try it out before you vote!

Pros

Great Carry
Nice base Dmg (skills)
Can take much Dmg
Can deal much Dmg
Can do nice ganks (with ult)

Cons

Mana runs out really fast
Enemys can flash out of the ult
Ulti need a bit skill, if you use him right you can turn teamfights

Main Spells:

1. ist really nice for escaping or chasing. I think its mostly better then Flash, cause Jarvan can replace it with Demacian Standard-> Dragon Strike.
2. is a nice dot to kill escaping enemies. I think it helps you alot cause Jarvan isn't the best chaser,

Other possibilitys:

Is also good for escaping ;)
Is good if you have to much manaproblems.
Not my favorite, but can be also usefull

- Is nice to lasthit creeps and versus tanks.

- This is your main-dmg skill. In combination with your E-skill. It knocked enemies in the air.

- Nice skill for escaping (slow) or towerdive.

- Good Passiv wich is nice for your team and yourselve.

- Really nice ulti, you can gank nice with it and also pull one champ out in teamfights, Also nice to prevent enemies escaping.

+ 5x With this combination you can stay a long time on your lane. It gives you armor and prepares the Hearth of Gold

Randuins give you all what a tanky champ need. And the active is nice in combination with Cataclysm(After Cataclysm ends)
Mercurys reduce the duration of stuns, slows etc. and give you magic resist.
It reduces the targets armor. Nice dmg item so I choose it as the second Item.
Gives you much health which you well need for survive..and you SLOW the target which is nice for chasing.
50 Magic resist is also important for you, but the primary effect is the passiv which is really nice especially against Karthus.
/ / Will be a situational item. If you need Dmg choose Infinity Edge, if you play agains champs like Xin Zhao you could need Thornmail and vs champs like Annie Force of Nature is really nice.

I hope you let some constructive comments here. I will complete my guide and write sth. more about masteries, taktics and runes. I also want to improve my grammar and misspellings.
And sorry for my bad english ;)

ENJOY