The tank item to fix it all!!!
Right now, pure tanks are having a problem with their defensive options and the problem surrounding it is.
Now, I'm not saying these items are bad for game health, but recently the AD&AP buff granted by dragon allows people to build flat penetration and crush tanks like they were made of paper.
But the reason that tank items are getting buffed is because, these broken champions can buy 1 defensive item and abuse it. Looking at you 
So, how about this? We give an tank item a passive that GRANTS BONUS ARMOR AND/OR MAGIC RESIST from items OTHER than itself.
The reason being, not itself is to force the person to build at least 2 tank items for it to have a real effect. And if the tank gets 4 items, then the effectiveness shines through
I think the best item to give the passive to 
, currently tanks are supposed to be the ones diving turrets and engaging for the team ( Not you 
) and the item on it's own seems lackluster for fighters to rush. If an Irelia rushes a ohmwrecker she gets much less benefit than say a 
The thing is, how much? 25%? 40%?
I'll leave that to the community
and 
. If a Tank cannot do either of those, they need some super niche to get by, like 
. That is the problem. Each Tank needs their own way of doing some super CC to initiate or peel or they will just be a bullet sponge.