Sup, Im TruFaulken, bringing another build for the LoL Community to play with. This is a guide and hence, you do not need to follow it right to the word, feel free to use it but please don't take it and post it somewhere else without my permission =]. That aside, I welcome you to my build on how to play Jarvan IV - Heavenly Blade, Shield of Light. (haha didnt have the brains to come up with a better name.)
Anyway this items shown above is not set and the Force of Naturecan always be substituted for a Thornmailor a Randouinsbut more on that later. Jarvan IV is a very good tanky/DPS and can dish out alot of amazing damage. In my opinion he should be build as a tank with sufficient attack damage and attack speed for him to really have an effectiveness in fights other than to tank.

PROS:
-Good Initiator
-Good Tank
-Good Survivability if built right
-Good Chaser and has decent amount of damage
-Has a good slow and shield and knock-up
-His Ultimate can be devastating and is good to stop fleeing champions
-Good Late Gamer

CONS
-Mana reliant early game (but this build will fix that)
-Can be CC'd and his ultimate can trap him to his death (if not used properly)
-He starts off slow early game
-Vulnerable to CC
-His ultimate can be flashed out of

I take exhaustfor the following reasons:
Exhaust counters dps champions as well as slow down escaping champions
Allows easy to chase champions as well as flee with ghost
Is also good in the middle of a teamfight, to negate the danger of an enemy DPS character or stop fleeing nukers

I also take ghostfor the following reasons:
Ghost helps you to catch fleeing champions and use your combo
Ghost is useful to get away before getting CC'd
Ghost is good for getting to a place quick (obviously) and can be helpful when you disengage an enemy then as they chase you, start hammering them down with your abilities as a 'second wave'.

I have tried some different Summoner Spells with Jarvan and here is details on the other spells that you should/shouldn't use:
Clairvoyance: Sometimes this spell is alright, but with Jarvan, it is a waste and can be replaced by a better spell for his overall game.
Clarity: Jarvan might need clarity early game, but it will be rendered useless during mid-late game when you have your Manarune.
Cleanse: is a decent spell to take with Jarvan as he will get Crowd Controlled alot and will need it to escape since he is mainly the initiator in teamfights.
Fortify: Fortify is good but I don't think Jarvan needs it and he isn't really a support.
Heal: As cheap as heal might be, it is ok but you don't need it with Jarvan since he's a tank and he can withstand alot of punishment.
Ignite: Ignite is also a decent spell for Jarvan as he is a Tanky DPS, so this can be used to finish off lucky foes who managed to flee...or so unlucky that you have ignite XD.
These two summoner spells are definitely not needed and are useless on Jarvan. Please don't take this, revive is just useless and you don't need more attack damage with Jarvan. Pointless.
Smite: Well I personally don't think Jarvan can jungle. But if it is possible, I will consider it.
Teleport: Is ok to defend towers and get around, I wouldn't recommend it but you can take it if you feel you need it.

With my runes, there are several different choices you can make in whether you want more survivability, more laning time or more damage output with armour pen. and so forth.

With my Marks I always take armour penetration because it just helps negate enemy champions from getting too much armour early game and hence provide you with more substantial damage. You could get attack speed mark runes however, I don't think you need it as he has a good starting attack speed.

With my Seals, I take either health per level or mana regen per level because sometimes (especially early game), if you don't like having being Out of Mana all the time, it is good to have extra mana regen. If you find that you can cope with a bit of OOM before you get your Tear of the Goddessthen I recommend you take health per level seals as it provides a bit more survivability.

With my glyphs, I take Magic Resist because I don't think there is anything else that could replace it. If you have any suggestions, I am open to them ^^. I also find Magic Resist to be good on Jarvan as he initiates alot of the team battles.

With my Quintessances , I have the choice again in taking armour penetration or flat health. Armour Penetration for extra damage early game and throughout mid game and the flat health for even more survivability during early game. This choice is up to you but I always get Armour Penetration Quints because I find it helps boosts Jarvan's damage output early-mid game.

My skill sequence to me, is more of a balance between all three abilities. I take the Demacian Standardfirst because I suppose, early game battles - it benefits alot more than having your Dragon Strikefirst. The way I see it is the extra attack speed and armour helps your team mate laning with you, and you have more of a chance to get FB. However, you can get Dragon Strike first if you feel you can deal the damage to kill them before they are under tower.
I take Golden Aegis third because I find that the shield helps defend against minor harassing from your enemy like Panthons Spear Shot or a ranged ability. After that, I max each ability in turn, primarily focusing on Demacian Standard and Dragon Strike a little bit more than the shield (as I max the final two levels last).

I take my selection for these reasons:
I take Dorans Shield because of the armour, health and health per second. I feel that he needs a bit of survivability early game before contributing to getting a mana item.
Next I take Mercury's Treads for the magic resist, and Jarvan being a Tanky DPS, needs its passive where it decreases the durations of most CC.
I build my first mana item which is the Tear of the Goddess. It provides decent mana regeneration and it almost cancels out your problem on being 'Out of Mana'. (I finish this item with a Manamune as it is the most suitable item to finish off granting attack damage, mana, mana regen and a passive that you gain mana and 2% of that mana is converted into attack damage XD.)
I then build a bit of my Force of Nature (which can be substituted for an armour item or something else depending on the game and the team), negatron cloak provides enough Magic Resist for early game so I finish it later.
Now I build my B.F. Sword which gives me the damage I need to start dishing out massive carnage with my abilities and start getting more kills. As he is a tanky/DPS, he is effective at taking down enemies with his combo: Demacian Standard, Dragon Strike, Golden Aegis.
I finish Manamune from Tear of the Goddess and as stated above, it provides more attack damage and solves your mana problems.
I finish my Force of Nature which gives me the Magic Resist I need and the health regeneration to keep me in-lane. (As I have said before, there is a section under this one that provides information of some optional items that you can replace. E.g. Thornmail or Randouins instead of Force of Nature.
I begin building my Starks Fervor as it is a great and crucial item (in my opinion) for Jarvan. It helps build his attack speed and it decreases surrounding enemies' armour by 20. Lifesteal is also very effective on Jarvan as he is a tanky/DPS. (this works hand in hand with Demacian Standard, granting even more bonus attack speed.)
Now you should be getting alot of kills, maybe farming up alot of minions with Dragon Strike and Demacian Standard. You should be well on your way to building an Infinity Edge which gives your Heavenly Blade the power it needs to cut down any foe. It provides heaps of attack damage and a little critical chance which helps a little but not much.

YOU CAN CHOOSE FROM THESE TWO ITEMS TO FINISH
Banshees Veil is useful for preventing too much Crowd Control from going on. It also helps a bit with survivability against good casters like Veigar or Leblanc. (You can also build a Guardian Angel's suggested in optional items)
Now I finally get The Black Cleaver as my final item because it gives me more attack speed (might not need it) and more damage. However the main reason why I get The Black Cleaver is because of its passive that shreds your target's armour by 15 for 5 seconds. This is effective working hand in hand with Starks Fervor which also lowers armour.

Here are some other items you may want to choose, it all depends on player composition and what your devious enemies are up to:
Wardens Mail can replace Force of Nature in the main build as to counter DPS and attack damage champions. This further builds into a Randouins Omen which grants you decent amount of armour, health and health regen.
Randouins Omen as stated above. Can replace Force of Nature.
Thornmail is great for countering those sneaky little DPS champions who like to kill people in a rapid succession of attacks. This item will provide the passive that will have them deal damage to themselves after they damage you. Win-Lose situation XD. Thornmail can replace Force of Nature in the main build.
Guardian Angel is a very capable item and can replace Banshees Veil if you think you are tanking overtime and dying too much for the team. This will help provide survivability and life after death XD.
Frozen Mallet is a good item to get if you will be doing more tanking and initiating than trying to get kills while tanking. It provides a good slow passive and it supports more health and survivability. If you can fit this into the build, it is a decent item to have.
Atmas Impaler is also a good item if you want to be more of the tanky type rather than a DPS/damage type. It gives armour and it deals an amount of damage from the percentage of your max health. (could work hand in hand with health items like Frozen Mallet and others.)
Bloodthirster is an effective item however, it grants more lifesteal and with your Stark's Fervor, you should have enough. If you feel you need more lifesteal rather than shredding armour with The Black Cleaver, feel free to get this item in its stead.
Hexdrinker is a good item for the purpose of tanking well in teamfights. It grants armour, and it provides a small shield that protects you when you are less than 30% of your health.

Jarvan's build mostly depends on your team's composition, your enemy's composition and the items that they get. It also depends if you need to be a more Tanky DPS Jarvan or a Solid Tank Jarvan. For now, I'll explain how to achieve a good laning phase with Tanky DPS Jarvan.

EARLY/MID/LATE GAME
In Early Game, I get afor survivability and I start off with Demacian Standard that helps with fending off an early laning battle between you and your enemies. Early Game, it should be relaxed, harrassing them only when neccessary with Dragon Strike or Demacian Standard. When you reach level 3, you should have all three abilities and you could try and set up a good gank from the bushes with your laning partner. The combo is Demacian Standard, Dragon Strike, Golden Aegis and if needed, use your Ultimate Cataclysm and repeat the combo. Remember that he can deal lots of damage with his attack speed and damage from his items. So don't be afraid to chase and auto-attack them to death when your abilities are on cooldown. Make sure you know when to withdraw and to attack, because sometimes that makes a difference. With lifesteal, Jarvan can survive most counter-fights. For example, if an enemy champion like Ashe is trying to take you down while you are on low health, do your combo, set up your shield (Golden Aegis) and use the extra health (from the shield) to run a bit away from your pursuer. If she chases you, abruptly turn back and deal your combo or use your ulti because that is very effective in getting lots of damage on your enemy. Also remember that you can use Demacian Standard and Dragon Strike to escape bad situations like the enemy team has ganked you at Dragon or in the Jungle. You can throw a standard over the wall and use dragon strike to pull yourself through it, saving you from a devastating gank from enemies.

[Will add more when I have the time. Been up all evening lololol.]

~The Right Way to Use Cataclysm~

To use it as a last resort when 1v1-ing an enemy champion, to take them down when they are on Half Health or lower.

To use it to trap fleeing enemies (1 or 2 enemies) then deal damage to them or use your Demacian Standard and Dragon Strike to get out and leave them as prey for your team mates.

To use it to intiate against a 5v5 teamfight, always aim for an enemy champion who IS NOT A TANK. Do not focus the tank, focus casters and champions who are just a nuisance to you like Master Yi

It is important that you watch out for enemy champions who carry the Summoner Spell 'Flash' who can flash out of your ultimate and run away. Of course, if you need the extra damage to kill them with your ultimate, they would be dead ^^

You can use to to delay your enemies from running away and give extra time for your allies to catch up and help take down the other team

Here are a few examples of a mash-up of builds you can use against different enemy champions:

TANKY DPS: Playing Against A Team of Mainly Casters

TANKY DPS: Playing Against A Team of Mainly DPS/AD Champions
OR(don't buy if you went for Thornmail)OR
SOLID TANK: Playing Against A Mixed Team
Check Out: Prince Jarvan - The Tank, By Kalkin

Farming is fairly easy with Jarvan. In Early Game, Jarvan like most champions would just auto-attack and last hit minions to gain gold. He deals a significant amount of damage early game and with Demacian Standard, he deals more faster (with attack speed).

When you reach level three in the game, you can start throwing your Demacian Standardbehind Caster Minions and use Dragon Striketo deal extra magic damage and you should be able to damage the minions ALOT or kill them and gain lots of gold. If enemy champions are nearby, right after you transition to Dragon Strike, quickly tap Golden Aegisto shield you from damage and effectively slow everything around you.

This is basically his farming method the whole game.

Tank, Support, Harass, Snare, Slow
Maokai is a great champion to lane with because of his snare and it works hand in hand with your ultimate. When you cst Cataclysm and trap your enemy(ies), Maokai casts his Ultimate and as your Ultimate Barrier fades, he can activate it to deal extra damage whilst they are in the circle. Maokai is also a very good harasser and helps take down enemies easily.
Stun, Burst, Tough
Poppy excels being your fellow laner as she is so good at dwindling your enemies' health. Either you set up your knock-up with Demacian Standard and Dragon Strike or she stuns them into a wall as you follow-up with the knock-up. It is just an amazing combo and the amount of CC and damange from harassing will make your enemies cry and call you 'OP'. Her ultimate is also very good when jumping towers and that gives you cover to either Ultimate yourself to deal damage and trap them or jump in with Dragon Strike.

MORE STILL TO COME

In summary, Jarvan is a very good champion to play if your looking for someone who can dish out decent amounts of damage and tank at the same time. He is fun and has some cool effects and pleasant jokes. I am open to suggestions of improvement and please rate the guide, explain your vote and have fun!

GAME SCORES SCREENSHOTS YET TO COME

4/4/0 (in a practice against people)
7/4/19 (in normal game) CLICK HERE
3/3/6 (in normal game where I tanked towers and dove in with Amumu to give cover for Poppy and Vladimir to take out enemy champions. Still did fairly decent amounts of damage.) CLICK HERE
Many thanks to Jazcav who provived many kind suggestions and brought this to life. Jazzie, <3

2011-03-3 Guide Created

2011-03-3 More to come: Who to Lane with, Optional Summoner Spells, Examples of Counter-Builds, Example of Game Scores

2011-03-3 Screenshot links added, finished Example of Counter Builds, added few game scores, Tweaked Build to start with meki pendant and gradually finish with Tear of the Goddess and Mercury Treads, added an item to Optional Items Section, Added few champions to the guide (laning teammates)