Can we redesign Swain please?
There's no reason he should win match-ups just because he has a point-and-click damage amp that does a lot of damage on its own. Because all he needs is E for damage, this means if you decide to engage on him, he's just going to peel for himself and throw more dots on you while kiting you and healing.
If you don't engage on him you either aren't farming, or eating his E over and over. If your jungler can't afford to neglect other lanes for a while, there's not much that can be done about it.
Either E's range needs to be lowered so he's more at risk for using it, its mana cost needs to go up, or his entire kit has to be re-adjusted around his Q or W.
As far as Q or W go, you lower his E base damage (via removing pure base damage or the amplifier) but give him an amplifier on Q or W instead as compensation This makes it so he has to either land his snare or keep them in his Q. Personally, I would put it on Q since its similar to E, just people can walk out of it, albeit while slowed.
Its really stupid how on many champs you can't even farm because you'll just take another E for 1/3 of your health, even if he's opting for a catalyst start...There's nothing you can do against it unless you can have a champ with long-range wave-clear. Your damage is supposed to suffer for an investment like that, and it doesn't at all as Swain atm.