Here's how I think Jhin should be nerfed:

It is simple: Simply Change his ult.

Curtain Call: Cooldown: 250 / 225 / 200 seconds / Cost: 100% of current mana / Range: 1000 / 1250 / 1500 / Maximum channeling time: 5 seconds

First Cast: slows himself to 100 movement speed, not allowing himself to turn to any direction and channeling himself.

Second Cast: shoots all Champion at the target direction, dealing [600 / 900 / 1200 (+0.1 AD)] times each second channeled physical damage to all enemy champion within 's Conic Range.

P.S. 's conic range is fully shown through enemy champions as well. If he cancels the ult, then he receives half the cooldown and mana used.

So what do you think?