Im going to keep it short and sweet. J4 can be played top, jungle, and mid (rarely) in summoners rift. I believe if J4 W/shield would scale with AP, it could open up some new game play for him. His E poke would be stronger and when he goes in the shield will keep him alive longer. Just an idea for an old school champ. 
I used to play J4 support and he has plenty of utility for it
Passive: % health damage for lane harass/all in
Q: armor shread and a knockup with the flag 'n drag
W: AoE slow and a shield to soak some damaged
E:AoE attack speed buff for seiging and early game harass
R: it's a ring trap, it's what everyone knows him for, combo this shit level 6 with someone like 
or
lol no
i dont understand why you want it to scale with AP for him to be played as a support.
how would that change it to a point to make him viable as a support?
it is already a slow. it shields jarvan based on his max hp per enemy hit by the slow.
it does nothing for the adc in lane other then the slow.
anything can be support if your adc is willing :^), but on a side note pls no because then he'll just use it elsewhere and why do you want him ap?
