Hi guys , I play Jarvan IV since he came out , almost every game and actually became my favorite character . I tried many builds but this one works best for me :) It is my first build here , so it is not gonna be to fancy , but hope u gonna like it !!!

Pros / Cons

Pros :
knock up
escape mechanism
slow
great passive spell damage
block damage

Cons :
Vulnerable to c.c.
not enough mana
low on HP early game

Runes

Jarvan IV is powerful assassin who can get in and escape from battles easy , that is why i use Greater Mark of Desolation , Greater Quintessence of Desolation and Greater Seal of Alacrity .On the other side this character has some bonus armor from the passive of DEMACIAN STANDARD but not so much HP and laning vs 2 AP characters can get him into trouble ;) and i think some magic resist could help a lot for early game , that is why the last rune i use is Greater Glyph of Warding

Summoner Spells

TOP SPELLS :

Ignite : Could be very useful early game when u need this last finish . Jarvan can get out of MP pretty easy so this this could be useful in moments like that .

Cleanse : Could be very useful for this champion but i use mercury's treads in my build so i think its enough :)

Flash : One of mu favorite spells in game , but i think it is not the right one for this champ , it could help a lot when being ganked , but i think demacian standard is enough and has same effect with even bigger range , so i don't think this spell is right for this character

Masteries

I play Jarvan mainly offense 21/9/0 , because i think with this build he has enough hp and resistance , but if u want u can choose defense masteries

Skills

Jarvan's Skills make him one of the best gankers in game . He has : slow , knocks up , he is distance closer , and his passive does great damage , combined with slow and ghost , what else u could want ?
DEMACIAN STANDARD gives the necessary armor and attack speed and the best thing is it gives the same aura to nearby allied champions which is a great plus for team
GOLDENAEGIS very helpful spell giving you not only shield which absorbs damage but slows the enemies as well which helps greatly in chasing champions
DRAGON STRIKE combined with DEMACIAN STANDARD helps to close the distance for getting in battles ( knocking the enemies up ) as well as escaping
this is the icing of the cake in chasing , even if the enemy champions has chance to escape or uses flash this will do the work :) it can save allied champions as well

Items

CORE ITEMS : :

Last Whisper is great item for Jarvan , everything he needs early game it boost him with some damage and a lot of armor penetration , combined with these runes make him a great killer
Frozen Mallet is the best item for this champion it gives him everyhing he needs - some HP a little damage and more slow ;) which makes him a NIGHTMARE for every enemy trying to escape
Veil - do i really have to talk about it ? This is the icing on the cake , mid game it gives you the needed magic resistance and shield that blocks spell every 30 sec . You now have all the needed resistance hp and armor , and can continue on damage :)