I tried the new thornmail on Pbe
it is actually nerfed badly, the damage of thornmail is meant to be against the heavy auto attackers, I understand it's nice to give it att speed/healing reduction passive that helps against the auto attackers but why would you nerf the only 100 armor item in game to 75 armor and reduce it's damage almost making it no more counter for the full heavy attackers.
The magic damage of thornmail used to be a counter for Adcs like master yi, draven, jinx etc... because the reflected damage was pretty good while it takes % of your enemy damage and % of ur armor as bonus magic damage so it was pretty unique and nice counter item.
So far Riot added 2 nice passive, made the item more expensive that's fine but why would u nerf the damage badly? and why would u take off the only 100 armor in game to 75? i don't care if u make the thornmail even more exepensive to maybe 3500 + i don't care really but at least the 100 armor + same magic damage dealt always gotta be same while adding the hp + unique passives. so it will always be the unique counter item against heavy auto attackers.