if you don't need a tank or are fed follow this guide...

have not tested in ranked games

as you can tell this is a very short guide(basically just the build's i use), i may add more to it later but for now if you want to know how to play as jarvan IV i would advise you to follow this guide below.

www.mobafire.com/league-of-legends/build/jarvan-tank-offtank-you-cant-kill-me-but-i-can-kill-you-114777

i would also like to credit them for as you may have noticed the first half of my build follows their's.

build 1 is for full crit damage(you can replace warmogs with phantom dancer if you want to go crazy)
build 2 is more tanky with some added crowd control

Pros:

-ult works great to gank
-late game with this build deals very large amounts of damage(crit 1000+ half of time)
-still tanker than many dps champs(3000+ health 100+ armour)
-can go any lane(all lanes work great with jarvan 1v1 top is best)
-helpful in team fights with his demacian standard
-has many range skills
-he is a prince

cons:

-much less tanky than other jarvan builds
-ult can sometimes end up worse for you than them
-melee(bad against range dps)
-no good escape(get flash or ghost if you want)
-he is up himself :)

normally i only play like this in a game where if
:i am fed
:we already have a tank
:just for fun

early game

in short

-i mostly try to pick 1v1 top lane if both teams are jungling.
-i might go mid which can be a good idea if your current mid isent doing well or when other people don't want mid
-farm minions/champs:)

i lvl up dragon strike first because it can do some good harass and will take off good damage on level 2 i get demacian standard because you can use it with dragon strike to pull you in quickly and knock minions/champs into the air(if dragon strike hits your demacian standard it pulls you to it)it is also another good harass with an attack speed and armoud boost. from then on i level dragon strike whenever i get the chance and demacian standard second alot of the time i don't put any points into golden aegis untill level 8 but you can at lvl 3 if you want of corse you want to put a point into cataclysm whenever you can

mid/late game

this is where the damage starts to stack up, i use my teleport to push minions/protect towers and gank anyone who gives me the chance.

in team fights i drop a flag and dragon strike in and then use my shield (you can often die this way if your not careful) thou alot of times people will try to run if you have cataclysm use it on them. this can also be a good idea if the fight is going badly you can use cataclysm on the enemy team which will trap alot of them and give your team a chance to escape thou you will die. also try not to trap your alredy fleeing team :)

please give any tips in comments and don't down vote if i've misspell a word somewhere or for gramor tell me and i will fix. also try the build before you down vote thou up voters can do that before trying :)