Dark Horses - Solo Lane Assassin Jarvan IV

Fear the flag
Jarvan IV is most commonly played in the jungle, built as a tank with high mobility and crowd control to keep his enemies in line with strong gank pressure. While the idea of tanking damage for his people is all very nice and princely, we're going to focus on Jarvan IV's ability to do the dirty damaging work by himself.
Lane bully of Demacia
Jarvan can get off to a strong start during laning phase, thanks to his threat of constant poke with Dragon Strike (Q) and the damage from his passive (Martial Cadence), which adds 10% of the enemy's current health as bonus physical damage to his auto-attack. If you can use his tools wisely in lane, it shouldn't be too hard to grind down your opponent's health low enough to force them to go back to base or risk giving up a kill.
Tools to dodge ganks or set them up
The tools that make Jarvan a powerful jungler also serve him well for dealing with enemy junglers; specifically, his E+Q combo (also known as the Flag 'n' Drag) quickly puts him in position to avoid trouble (or start his own). When he's out of position in lane and the enemy jungler comes to gank, he can use this combo to knock up the jungler and escape without using Flash. Of course, he can also use his E+Q combo to quickly roam the map and gank other lanes, just like he does in the jungle.
Turn the enemy carries into a squishkebab
We’ve talked about his damage and how strong Jarvan can be, but to really make a difference in the mid game Jarvan will need offensive items, especially the ones that have Armor Penetration. After laning phase, your job in teamfights is to jump onto the carries and explode them.

Can't deal with damage​

We're used to thinking of Jarvan as a solid tank in his standard jungle role, but if you go for a full damage build, he won't be able to handle taking damage very well. His W gives you a shield that slows enemies, which can be useful for buying you time and space to survive long enough for your teammates to help, but don't expect this Jarvan style to do well in longer fights.
All-in on teamfights
If you blew your full Jarvan IV combo and your team didn’t follow up, or your team didn’t win the team fight and you’re out of cooldowns, you can consider yourself pretty much dead. Jarvan's assassination potential lies in his ability to burst a single enemy and hold him behind, especially in the early game. Remember: Princes don't live long enough to become kings unless they only pick fights they know they'll win.
Need to manage your mana
Jarvan is very mana-reliant, so make sure you keep a reserve pool of mana handy or you might have a problem finishing a combo or escaping a gank. If you need a little more safety in your laning phase, consider picking up a Crystal Flask to quench Jarvan's mana thirst.