MR Is honestly too available.
It is crippling when you are AP and the entire enemy team has maw/merc scim. Even the support has a lot of MR, if an AP builds full armor, they are crippled heavily. Oh but if AD wants "extra protection" That's fine, here we will even give you some attack damage with it.
fair
that
you
mages
get
to
one
shot
us?
that's a level of desperation I hope to never reach.

isn't that many, and please don't include
as mage items, diving in face first to deal damage doesn't make sense for a mage, and GLP might as well not even be an item in the game. I've seen it built once and it was by me testing a Swain build and it was a bad choice.
, and shields from items like
, and a nice item that gets rid of CC
.