I know Swain needed buffs, but holy shit, Riot.
I just played a match against him, he's completely broken.
His damage is just too much and once he hits level 6 he's nearly unkillable.
On top of that he forces the opponent to stray from their optimal build path to go for Morello and Executioner's which in turns make him continue to massively out trade the opponent until later in the game.
Swain currently has a 58% winrate at games below 25 minutes and a 61% winrate at 25-30 minutes, his late game falls off to 51% which is ok.
The PBE nerfs do not address this at all. His damage powerspike at level 3 continues the exact same, with a very small nerf at levels 4 and beyond, and his sustain was only changed against champions. He will be weaker in late game teamfights but he will continue to hardly oppress his lane opponent by sustaining off minions. His early game damage and sustain needs to be addressed, not his mid/late game.