User blog comment:Baakdraft/Jarvan III, King of Demacia/@comment-77.77.166.109-20130205182715/@comment-6316152-20130205191430

Q is meant to be conceptually like a mix between both Ahri and Orianna's Q in that you throw it out and it lands (much like Orianna's ball) but then can be activated again within a window to be summoned back (much like the full effect of Ahri's Q). In doing this you can effectively aim the shot in hopes of scoring a stun by hitting an opponent with both the outgoing hammer and incoming.

As for the passive it's meant to be nearly non-existant in the early game but begin to scale hard into the late game making him naturally tanky, much like Thresh would become by acquiring souls. His passive only effectively scales with your team's build so a team that's largely squishy really benefits him little overall.

E is not much different than playing a Malz, Yorick, or Elise other than you getting an opportunity to choose whether or not you want your cast to be used offensively or defensively. Though cooldown and uptime may need tweaks it effectively allows him to still solo top against AP and ranged AD without being stuck under his turret.

And as for R, it's a cross shaped skillshot with a fairly narrow hit radius in mind, it's not like a fiddle, amumu, or nunu where it effects a large area, but more like a blitzcrank grab breaking out in 4 directions. So with the ability to A. miss the skill shot, and B. potentially outrun it I do not personally feel the ability is OP for it's learning curve or cooldown. As for initial base damage it is on par for most bruiser type champions, though tweaking can most certainly be done to properly balance it throughout the course of the game.