In all seriousness, if you take a
a
and a
on Jarvan, a single autoattack can deal over 25% of your target's health, even if the opponent started at maximum health. The duelist's saber will then help you kill the enemy champion (seriously, I'm surprised people don't play this build more).
He has an incredible initiate (a ranged knock up), armor penetration built into his kit, and if his ultimate is up, your target literally cannot escape (save burning a flash or a dash). And don't worry, his kit also gives you relevance during team fights!
From there, you can choose a build that increases his comparative mobility ever further:

Or you can go the bruiser route, which looks exactly the same, only with the mercury treads replaced by either either spirit visage, banshee's veil, or the armor item of your choice.