Jarvan is one of the best junglers in the league with his early "e" "q" combination. He has a strong passive versus neautral monsters and excels as a tanky dps champion.

I have chosen this rune build because Jarvan jungle ofc needs good armor and attack damage early game. I have taken magic resist glyphs to improve the mid lane ganks, so you can gank with less hp without risking death.

I have chosen 9-21-0 because despite of his strong AD potential Jarvan is a tank and he needs strong points in armor and damage reduction.

I have 9 points in offense to increase his early jungle potential.

Utility isn't really usefull anymore in the league. Only for maybe a support or ap with need for mana regen.

Cloth and 5 healt potions is standard for any jungler. This is maybe not so innovative but it's still the best way to get good cs in early jungle.

Wriggles lantern again is a must for this offensive jungler. And with the wriggle active you can also support your top lane with a good 3min ward.

Mercury's treads is the standard shoes, but in a game against all AD consider buy ninja tabi.

Frozen Mallet and Atmas impalaer gives you excellent survivability and damage and are the two single most important items for Jarvan jungler.

Last Whisper gives great damage output and counters the opponent tank.

After Last Whisper the build is more free to innovation. I prefer banshees veil because it counters burst champions and gives ekstra attack damage from atmas.

(Other options is trinity force or trinity edge for more damage)

Guardian angel is for very long games for survivability and tankynees.

I think flash is essential for almost all champions in the league, because it gives you the aggresiveness needed to push lanes and it can also funktion as a offensive move.

fx flashing over walls to trap opponets in your Jarvan ult.

Other usable spells will be (exhaust for more offensive players, teleport for good ganking on team, clairvoyance if your team needs support spell)