@Riot: Here is what Swain changes need to be to make him come even close to the current line up.

Passive: CD on the Pull needs to be per champ not the passive it self. If Lux Roots two champs, Swain should be able to pull both of them.

Q: Revert the Range nerf. It Feels really bad. OR Add a SLOW to his Q if hit at max range (like Akali's Q)

W: This needs to pop faster. With the Passive change to NEEDING Stacks to sustain in lane you have to hit W and its Delay makes it so even slowed champs can walk out of it. (Unless you make the chances to Q and E, then its fine)

E: Should be a wave out and back that hits. Getting hit by the Wave going out (away from Swain) should slow by 20%. Getting hit by the Return wave and you are slowed (by any slow) should Root for 1.5s

R: Changes are good BUT Mords passive is stronger then Swains Ult. It does more damage and heals for more. I suggest that for each stack Swain has of his Passive gives his Ult +1 Damage and Healing

Swain does not build a lot of AP (he is better with lots of HPs) so his damage should be more scaling with his Stacks and not his AP as much.

With this Swain would be a comparable pick to "A" Tier champs in the current meta.