Here is how I like to build Jarvan, if you don't like it you can suck it. This is a pure tank build, because that's how I build Jarvan and it seems to work pretty damn well.

The stats at the top of the page are kinda wrong because they don't account for the extra 450 health that Warmog's Armor gets when you kill minions and it doesn't add the extra AD from Atma's Impaler, so the real stats are: health is close to 5000 and ad is around 240.

First off, you need your runes:

Greater mark of desolation x9 for the general damage.

Greater Seal of Armor x9, Greater Glyph of Magic Resist x9 and Greater Quintessence of Health x3 for the general tankyness, this is a tank build after all.

Simple, straightforward 0/21/9

important ones are: Defensive Mastery , to survive in the jungle and Utility Mastery so you can keep those precious buffs longer.

You can also go 1/20/9 or 1/19/10 or 0/20/10 if you want that extra point in Plentiful Bounty or to get the second point in your Utility Mastery .

Items you can go any number of ways on, the one seen above is the one that i use most often, because it gives a ton of sustainability as well as pretty good damage.

Core items: Sunfire Aegis and Force of Nature and Mercury's Treads or Ninja Tabi

in my opinion, these three items are the staple items of any tank, meaning that if you are playing a tank and you finish the game without a sunfire, a force of nature and one of the boots that are above, you did something terribly wrong. On the boots, I generally go with merc treads virtually every time, but if the other team has very little or no cc then ninja tabi are actually better.

Personally I like to stack health so that when I get that Atma's Impaler I can just wreck everyone, resulting in a lot of early game assists, and late game kills. (it also makes me feel invincible when I have 5k health) If you think this is dumb then here are some other viable options for tankyness:

Randuin's Omen
Aegis of the Legion
Guardian Angel
Quicksilver Sash
Frozen Heart
Thornmail
Warmog's Armor

These items are generally pretty situational, you should be able to know when to get these, aegis if your with a bunch of squishies, frozen heart or thornmail if you are getting rolled by an ad carry and so on...

If you would take the time to notice that i have listed just about every general "tank" item except for 1. That 1 is a Banshee's Veil. DO NOT GET A BANSHEE'S VEIL IF YOU ARE PLAYING A TANK!!!!!!!!! Banshees is an item for carries who are useless when they are stunned or silenced. You are a tank, you want to attract all of the stuns and silences and all the other cc that the other team has to throw at you because you are a manly man and can take it like a boss. If you are really afraid of cc I would suggest getting a Quicksilver Sash, cheaper than a banshees, gives just as much MR and can cleanse anything, and when i say anything i mean ANYTHING. If Mord ults you, just pop your QsS and it's gone, same with any suppress, stun, silence slow, even poisons and Zilean's pesky time bombs.

Skill sequence r->e->w->q

What makes a good tank is not his/her base stats, its his/her skills. You want a good initiate and lots of cc and aoe damage.

Lets look at Amumu, probably the most op tank in the league.

Bandage Toss is an amazing initiate and has some cc
Despair aoe damage over time
Tantrum aoe burst
Curse of the Sad Mummy huge aoe cc and damage

Jarvan has 2 great initiates and some pretty good cc, which is why he is a better tank than a dps.

Dragon Strike

Shoots out in a line in front of jarvan, does damage and shreds armor. Not really useful for damage if your building tank, but its got other uses which we will come to later in this section.

Golden Aegis

Shield that scales with how many enemy champs you get with the aoe slow that activates when you pop it.

Demacian Standard

The most useful skill in all of jarvans mighty abilities. This standard can be thrown a great distance and acts as a ward for 8 seconds or so. It deals damage on impact, and you and all allied champions near it gain bonus attack speed and armor, which makes it great for taking turrets and just to have in the middle of a team fight. Little known fact you can teleport/leap strike/shunpo/whatever to Jarvan's standard while it is down. Tell all your friends, because nobody seems to know about this.

Cataclysm

Jarvan's ultimate. Probably my favorite ultimate in the game, just because it is so bad ***. It jumps onto an enemy champ, damaging them and creating a ring of terrain around them and yourself. This is an amazing initiate and is awesome for combos with other champs' ultimates. Pretty much anything that does a lot of damage in an area is great with cataclysm, the obvious ones would be Fidd's Crowstorm and Nunu's Absolute Zero, but it works well with pretty much any aoe ult, examples would be Bullet Time, death loctus, Glacial Storm, slicing malestrom, Soul Shackles, and Grand Skyfall.

Damacian Standard/Dragon Strike combo

This combo is so useful that I decided to give it its own section. When your standard is down and you hit it with your dragon strike you will be pulled to the standard, knocking up all enemys in your path. This skill can be used for almost anything. It's main purpose is an initiate to a team fight if they are grouped up, because you really don't want to cataclysm yourself in with their whole team, that's just stupid, but if you do, remember that you can always dash out of your ring faster than you can collapse it. Also, if you are trying to get away from chasing enemies you can use the combo to go through terrain. Remember that the standard and the dragon strike have the same range, so if you throw your flag, as long as you dont move you will be able to hit it.

For your jungle you want to use the basic mini golem to blue golem route... with a twist! Jarvan is one of the only champs that has a pretty good low level gank, and by low level I mean level 2. I like to gank mid at around 2:15. Its great because nobody sees it coming and with the knock up from the standard strike combo its an easy kill because mid lane is usually still level 1 at 2:15.

Anyways you want to go Mini Golems, Gank, Wraiths, Wolves, Blue, back, Red, gank. and after that you can do what ever you want. for more info on jungling in general go look up one of those excellent jungling guides here on mobafire.

The one spell that you need need need need need. Why you ask, BECAUSE YOU ARE A JUNGLER! AND ALL JUNGLERS RUN SMITE.

Flash is flash, and in my opinion all champs should run flash regardless of who they are and what they are building

Other viable options:

Ghost is always useful, because running fast is good

Exhaust is always useful to make people slow and do less damage

But as a tank you wont really be chasing anyone down so both of these spells are kinda useless.

This build may be small and weak now, but i will keep updating this guide until it is number 1.

here are some of my games from today to prove that this build does work.

8/22/11 - guide published
9/3/11 - General proofreading + added other mastery options + added to the skills section
10/2/11 - Added to the part about how to use your skills