@Meddler: Thornmail - Is it even workable?
Thornmail rarely (if ever) works these days. One MR item and its thorns damage basically evaporates and doesn't even meaningfully reduce enemy lifesteal. You basically run into an inverse of the old Zeke's Herald problem: you get Thornmail, and it gets countered by MR and lifesteal with no way of beating those two.
I recently had a Leona game where I had 500+ armor (enemy had 4 physicals), but the enemy team was simply LAUGHING at me for getting it, as it didn't even slow them in the slightest. Yes, some people have said I should have gotten more health, but they had Vayne and Fiora, who hard-counter all tanks. But beyond them, even their ZED was taking literally nothing from Thornmail procs, and he didn't have MR.
I have to ask if there's any plans to make Thornmail a worthwhile purchase, or if its mechanic is toxic. I'm guessing it's the latter, as it's a case of "invisible punishment" in that you get punished for attacking someone, but said punishment can't be strong or it's broken. Since it runs into this conundrum, I won't be surprised if you remove it for being unbalanceable, but is there a chance you might instead rework it?

. So yes, once you figure the other guy is probably going to take more effort into nullifying your 6 items with 2, buying more and more of the stuff becomes of lesser value assuming the other team is playing correctly and anticipating your build.