Quick Guide

Runes

Okay so for runes this is going to be a pretty simple explanation. Flat armor since physical damage is sort of crazy early game. Flat damage quints to make sure I can last hit easier and get some decent early game damage. Flat armor pen reds because of how jarvan functions. If you shred their armor then have penetration you get a TON of phys shred. For example, lets say the opponent has 100 armor. I get 26% shred, then 15 armor pen, then 15 more from brutalizer. I shred it to 76, then pen 30 reducing it to 46. Combo that with my passive and high Q base damage and you're going to make a lot of damage happen off of that armor pen.

Masteries

Okay these masteries are going to be pretty simple to explain. Lets look at it this way, you want to do massive damage and dunk dunk dunk. To do the most damage you're going to have to use this build. This is a decently standard 21/9 build focusing on health and damage, and a lot of damage at that. 

Summoner Spell

I don't really have much to say here unfortunately. Basically, flash/ignite is just the best right now. Why not get ghost? Because Jarvan already has 2 gap closer mechanics and EQ->flash->R means you can dunk from LITERALLY two screen lengths away. Ignite gives +5 damage (from masteries) so that's really important for early game. Other than tha somet things become really popular because they're really good. Flash/ignite fit this category. 

Skill Order

Dragon Strike Dragon Strike Extends Jarvan IV's lance dealing 70/115/160/205/250 (+1.2) physical damage and lowering the Armor of all enemies hit by 10/14/18/22/26% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path. Cost 45/50/55/60/65 Mana Range 0 Cooldown 10/9/8/7/6 Seconds		Dragon Strike Extends Jarvan IV's lance dealing 70 (+1.2) physical damage and lowering the Armor of all enemies hit by 10% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	Dragon Strike Extends Jarvan IV's lance dealing 115 (+1.2) physical damage and lowering the Armor of all enemies hit by 14% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.		Dragon Strike Extends Jarvan IV's lance dealing 160 (+1.2) physical damage and lowering the Armor of all enemies hit by 18% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.		Dragon Strike Extends Jarvan IV's lance dealing 205 (+1.2) physical damage and lowering the Armor of all enemies hit by 22% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.		Dragon Strike Extends Jarvan IV's lance dealing 250 (+1.2) physical damage and lowering the Armor of all enemies hit by 26% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.
Golden Aegis Golden Aegis Temporarily gains a shield that absorbs up to 50/90/130/170/210 (+20/30/40/50/60 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 15/20/25/30/35% for 2 seconds. Cost 45/50/55/60/65 Mana Range 0 Cooldown 20/18/16/14/12 Seconds				Golden Aegis Temporarily gains a shield that absorbs up to 50 (+20 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 15% for 2 seconds.										Golden Aegis Temporarily gains a shield that absorbs up to 90 (+30 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 20% for 2 seconds.	Golden Aegis Temporarily gains a shield that absorbs up to 130 (+40 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 25% for 2 seconds.		Golden Aegis Temporarily gains a shield that absorbs up to 170 (+50 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 30% for 2 seconds.	Golden Aegis Temporarily gains a shield that absorbs up to 210 (+60 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 35% for 2 seconds.
Demacian Standard Demacian Standard Passive: Gains 10/13/16/19/22% Attack Speed and 10/13/16/19/22 Armor. Active: Throws a Demacian Standard to a nearby area dealing 60/105/150/195/240 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 10/13/16/19/22% Attack Speed. Cost 55 Mana Range 860 Cooldown 13/13/13/13/13 Seconds	Demacian Standard Passive: Gains 10% Attack Speed and 10 Armor. Active: Throws a Demacian Standard to a nearby area dealing 60 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 10% Attack Speed.							Demacian Standard Passive: Gains 13% Attack Speed and 13 Armor. Active: Throws a Demacian Standard to a nearby area dealing 105 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 13% Attack Speed.		Demacian Standard Passive: Gains 16% Attack Speed and 16 Armor. Active: Throws a Demacian Standard to a nearby area dealing 150 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 16% Attack Speed.		Demacian Standard Passive: Gains 19% Attack Speed and 19 Armor. Active: Throws a Demacian Standard to a nearby area dealing 195 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 19% Attack Speed.	Demacian Standard Passive: Gains 22% Attack Speed and 22 Armor. Active: Throws a Demacian Standard to a nearby area dealing 240 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 22% Attack Speed.
Cataclysm Cataclysm Heroically leaps to an enemy Champion dealing 200/325/450 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain. Cost 100/125/150 Mana Range 0 Cooldown 120/105/90 Seconds						Cataclysm Heroically leaps to an enemy Champion dealing 200 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.					Cataclysm Heroically leaps to an enemy Champion dealing 325 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.					Cataclysm Heroically leaps to an enemy Champion dealing 450 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.
	E Demacian Standard Passive: Gains 10% Attack Speed and 10 Armor. Active: Throws a Demacian Standard to a nearby area dealing 60 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 10% Attack Speed.	Q Dragon Strike Extends Jarvan IV's lance dealing 70 (+1.2) physical damage and lowering the Armor of all enemies hit by 10% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	Q Dragon Strike Extends Jarvan IV's lance dealing 115 (+1.2) physical damage and lowering the Armor of all enemies hit by 14% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	W Golden Aegis Temporarily gains a shield that absorbs up to 50 (+20 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 15% for 2 seconds.	Q Dragon Strike Extends Jarvan IV's lance dealing 160 (+1.2) physical damage and lowering the Armor of all enemies hit by 18% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	R Cataclysm Heroically leaps to an enemy Champion dealing 200 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.	Q Dragon Strike Extends Jarvan IV's lance dealing 205 (+1.2) physical damage and lowering the Armor of all enemies hit by 22% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	E Demacian Standard Passive: Gains 13% Attack Speed and 13 Armor. Active: Throws a Demacian Standard to a nearby area dealing 105 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 13% Attack Speed.	Q Dragon Strike Extends Jarvan IV's lance dealing 250 (+1.2) physical damage and lowering the Armor of all enemies hit by 26% for 3 seconds. If the lance contacts Demacian Standard it will pull Jarvan IV to its location, knocking up enemies in his path.	E Demacian Standard Passive: Gains 16% Attack Speed and 16 Armor. Active: Throws a Demacian Standard to a nearby area dealing 150 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 16% Attack Speed.	R Cataclysm Heroically leaps to an enemy Champion dealing 325 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.	E Demacian Standard Passive: Gains 19% Attack Speed and 19 Armor. Active: Throws a Demacian Standard to a nearby area dealing 195 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 19% Attack Speed.	E Demacian Standard Passive: Gains 22% Attack Speed and 22 Armor. Active: Throws a Demacian Standard to a nearby area dealing 240 (+0.8*AP) magic damage to enemies. The Standard lasts for 8 seconds and grants surrounding allied champions 22% Attack Speed.	W Golden Aegis Temporarily gains a shield that absorbs up to 90 (+30 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 20% for 2 seconds.	W Golden Aegis Temporarily gains a shield that absorbs up to 130 (+40 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 25% for 2 seconds.	R Cataclysm Heroically leaps to an enemy Champion dealing 450 (+0.7) physical damage and creating an arena of impassable terrain around them for 3.5 seconds. Activate again to collapse the terrain.	W Golden Aegis Temporarily gains a shield that absorbs up to 170 (+50 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 30% for 2 seconds.	W Golden Aegis Temporarily gains a shield that absorbs up to 210 (+60 damage for each nearby enemy champion) damage for 5 seconds, and slows surrounding enemies by 35% for 2 seconds.
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18

Okay so far for skill order this one is hopefully going to be really simple to explain. You start with E because of the bonus armor. SOMETIMES (SOMETIMES) you'll start with Q against people like Vlad or Kennen but even then it'll often be better to just get the E bonus armor to mitigate their auto attacks until you can EQ combo properly. You max Q first for the armor shred and big damage. Then you max your E because you want that armor and attack speed to keep tearing people apart. Lastly you max your W which gives you sme decent survivability late game. Decent enough to not get stomped on anyway. 

Items

Starting Items

Starting items should 95% of the time be boots + 3 health pots. You aren't very escapey as Jarvan so you won't get away with silly things like a Doran's shield start or something like that. What's more, Jarvan is one of the greatest gank assisters so it really does make sense to help your jungler out by getting boots. Remember that a lot of Jarvan's playstyle is unselfishly killing enemies for your allies. Boots ensure you can do this.  Cloth armor will be decent in "oh crap" fights like against Riven, or Lee Sin, etc.

This is the ideal build you are shooting for. This should be what you fight tooth and claw to achieve. Once you get this build the appropriate response is to shout DUNKMASTA J in chat repeatedly while full health comboing people. To say this build does damage is like to say that labs are the best dogs. They just are so accept it. With this build you will legitimately be able to full health combo anything short of a tank. Even most bruisers will be killable if they havn't stacked on armor. 

Full Game Build

Okay some things MUST be noted about this build. 

• Your ideal build is Boots -> dorans -> hexdrinker -> ninja tabi -> brutalizer -> trinity. It is only then that you being to build the rest of this. 
• The ideal build against an enemy that does 0 magic damage is Boots -> dorans blade -> dorans -> ninja tabi -> brutalizer -> trinity -> hexdrinker. 
• Brutalizer is a core item and Black Cleaver adds a lot of damage too.
• Hexdrinker is also a core item and getting Maw will only be done once item capped (And probably last, it's overcost.) 
• Ninja tabi is interchangeable with Merc treads depending on your matchup. Please note however that Ninja tabi is way overstat for its cost and will often make you near unkillable to ranged carries for the majority of the game. 

Pro Commentary

Pros and Cons

Pros

• Dude, you're DUNKMASTA J.
• You can full health combo down anybody barring tanks.
• You remain tanky-ish enough to initiate many fights so long as you have proper team support.
• You maintain Jarvan's team fight utility, which is a lot of utility for an assassin (who get 0 typically.)

Cons

• You can't fight the burly bruisers like Olaf or Jax or such very well. In fact, you should probably avoid bruisers entirely until team fights when you can do 70% of their health and let your team finish. 
• It's really easy to mess up Jarvan's combo by missing. Also, he's kinda buggy.
• Jarvan does not have the best laning phase. 
• His mana is ridiculously low too. 

Counterpicks - Early/Mid/Also Early Game

This might need a little bit of explanation. Basically, I do NOT consider malphite a counter to Jarvan, regularly, because Jarvan can just push his lane then gank mid and get around Malphite. This is why I consider Ahri a counter pick, because she will 100% avoid every one of his ganks. What's more, Jarvan can ult on to even a black shielded Morgana to gank her easily with no ultimate. Because of Jarvan's ignore-top-and-gank-mid playstyle that often occurs the only tops that really counter him are the ones that can force him in to tower and completely stop him from roaming. That's Lee Sin and Darius right there. There really isn't such a thing as a late game counter to Jarvan since falling off late game as all bruisers do counters Jarvan on its own.

HOWEVER, since Jarvan is so good in team fights compared to other bruisers even ones that will completely stomp him 1v1 (Jax)  aren't a counter since he'll just beat them in team fights. For example, Jarvan can shred Jax's armor, knock him up, slow him, etc. Jarvan's team is bound to get the kill on Jax first due to Jarvan's higher burst and team buffs (his flag.) Jarvan can also IGNORE Jax and just trap people in his ultimate for kills, or just go for the kills himself since he's better at it than Jax. That's not just Jax though, I was just using Jax as a reference. Jarvan does this same thing to pretty much every bruiser.