What i do as jarvan

Ok so if you are blue side start red with q and line yourself at the side of the camp so you can hit all 3 with q after your leash and smite about 3 autos another q you finish it than eq towards blue buff do it as soon as it comes off cd then save ur eq when it comes back up than go into the bush right by blue buff if they dont see you just wait till it gets low and prepare to steal it with an eq then kill them or if they get low just kill them and take it if you are doing gromp start e and do the same thing

ps if you hit level 3 and your going to gank level up your w instead of q

You do tons of damage to squishes and few tanks can tangle with you either always look for picks on squishes if you land eq than auto than when they flash ult if they don't have it and they are about to die if u need the extra damage just ult also you can keep people occupied when your team is dead if you have enough cdr you can keep eqing back to your flag about 3 times then your e will be back up just keep knocking them up over and over if they have low cc until you finally kill them 2v1 or 3v1 also always invade level two after your first camp unless your vs someone who clears fast or someone who can easily kill you surprisingly you would think thats leesin but somehow you will almost always beat him 1v1 until he hits 6

Great pick into most teams only champs that mess him up are the hard ones mentioned above

Pros

High Burst Damage
Lots of cc
Lots of Moblity
Very tanky
Q Gives long range poke
Cons

Kind of falls of late game compared to other champs
If you miss eq and your not fed you cant do much
Kind of squishy till you get tank items
Lots of Counter play to his kit

In team fights always go for there squishy fed target unless they have a zhonyas even if your team is crying about peeling ignore it always focus there back line unless you cant kill them then that is when you should peel when peeling ult a tank that isnt on one of your squishys then eq out and focus on whoever is closest to your back line

Always gank unless they are pushed to tower or its a hiemer dinger even if its just to walk up and q or auto a few times still helps alot

First Guide any criticism Is highly welcomed ^.^ just wanted to say what i do as j4 in words if this gets good feedback will make a guide for j4 top and support and mid :D