Hi, I'm a diamond tank/bruiser main and I am pretty concerned with the current state of their itemization as of this Patch release on the 29th of October. TLDR would be, MR items are amazing and armor items should be like them, because they fell really lackluster and has a lack of diversity.
Let's start with Magic resistances itemization. The current state of the cowl line is EXACTLY what tank items should be. An item with good stats that helps you deal with a certain type of damage, that is slot efficient and that has a purpose. The downside? It's really expensive to build, but when you complete it, you fell rewarded. The current banshees and visage do that perfectly with a good amount of health, a great amount of magic resistances and with a good passive that gives you diversity in items since the spell shield can be more valuable than CDR and healing in some cases.
Hexdrinker/Maw are in a pretty good state as well. The fact Maw has bonus healing when lower and armor pen makes it a lot more attractive as a damage item for many bruisers like Olaf, Jax or Darius who can utilize those stats and this passive properly. It's also a good adc item now, so it will see more play in general and feels like a good hybrid damage/defensive items with good damage and good anti burst defense.
While those items are in a pretty good state, others in the magic resistance line aren't. The item that really dissapoints me is Wits end. It currently got given 10 extra MR, but lost 10% attack speed and was made 300 gold more expensive. Compared to othe other MR items, It's extremely bad. It got it's cost increased without getting any meaningful stats boost, which will make it even less seen. The current problem with wits end is that it's build path is total shit and that it's too expensive. These changes makes it even worse since you increase the cost and you don't improve the build order. The item shouldn't cost more than 2600g with it's current stats to even be considered building. It should also get a "mini wits end" component in it's build path + a recurve bow. This "'mini wits end' should be a Dagger + null magic and give you 20 magic damage on hit. That way, on your first recall, you can get a good item that gives you some attack speed, some MR and useful damage, just like hexdrinker. Currently, on your first recall you're forced to get a recurve bow or 2x dagger + a null magic, which feel really bad to buy as a first back and makes you insanely weak compared to buying buys a phage or a hexdrinker.
Now, let's look at armor itemization and what is wrong with it. I'll list down items and cover them one by one.
1. Sunfire cape: It is bad and always be bad unless you give it meaningful stats or increase the damage of it. Currently, the damage from it is just way too low when you complete it and it doesn't give you good tank stats to be considered buying on most champions outside of Shen who needs it for waveclear. I like the attempt of making it a bit more expensive and giving it 50 extra health, but you should take a step further. Make it 3000 gold, yes, 3000 gold, but give it 550 health and 60 armor with 30 damage per second + 1 per level. It would actually have decent stats that compares to deadman's plate and have a good enough damage to be considered building.
2. Iceborn Gauntlet: I'm not going to lie, I'm currently in love with this item and have built way more than I should have in my testing. It's a great item in it's current state, since it gives you another option to get 20 CDR from, making it a good rival to frozen heart for tanks / bruiser. The armor isn't as bad now, so it feels better to build as a defensive item and the Sheen AoE is amazing now. It's so good that It can literally replace sunfire as a tank waveclear item, because it gives you CDR, Mana and CC, which sunfire does not. It also helps with sticking power and trading in lane, so I feel like this item is a pretty good spot and confirms that sunfire is still a trash tier item unless it gets help.
3. Deadman's plate: The best armor item in the game. No avoiding it, it has good armor, good health and helps you get on targets with MS boost and a slow once you reach them while also giving you damage. In the current state of armor itemization, that and iceborn gauntlet are almost the only armor items worth buying outside of ninja tabi.
4. Frozen heart: Give it 100 armor back. Was it too strong? Yes. Did it need to get nerfed? Yes, but not in it's slot effecienty. Before it was 2450 gold, which is stupidly cheap. Now, it's 2850 gold, which makes it harder to complete, but feels less rewarding when complete. Giving it 100 armor back who make it a solid tank item again and would make you consider twice before getting iceborn gauntlet, because you'd miss out on a lot of defense. At the moment the defense it gives and the higher cost makes it less attractive than iceborn gauntlet on almost every champions.
5. Randuin's omen: Please stop hitting it, it's already dead. Seriously, this item has been nerfed more times than shaco, nocturne and irelia combined. Increasing it's cost for a poor 50 health bonus isn't going to make it a good item unless the ennemie team is literally 3 ADCs who relies on crit or Ashe+ yasuo / Tryndamere. The stats on it are just too bad and the slow got nerfed to the point that deadman's slow is better. The reduce damage from crit is nice, but it's not reliable tankiness and only helps you against a limited about of damage and champions. What makes deadman's, banshees and visage good is that they have good stats against the damage you're itemizing against, but doesn't feel useless against the other one. Randuin's is ok against physical damage, especially auto attack damage, but it's pretty bad against AD casters because it doesn't have enough health or armor for it's cost and it's bad against magic damage compared to deadman's because of it's lack of health. The item should have AT LEAST 500 health and possibly 65 armor to make it a bit more in lane with other tank items since it's so god damn expensive. Banshees and visage give you 500 health and 70 MR for the same cost, so randuin's just looks outclassed and weak at it'S current cost.
6. Ohmwrecker: A very interesting item with a lot of potential that remains in the dumpster and never being bought because of the sunfire effect. It doesn't have enough health, it doesn't have enough armor. The active is actually game changing and could potentially be meta breaking, but since the item has such poor stats, it's never going to see play. The active is pretty clear, it allows teams who are bad at sieging to kill turrets or dive them when they can't deal with a constant waveclearing team who just stalls out the game. This allows a team with melee focused champions and more all in style to actually be able to deal with sieges and end the game if they get a lead. This could potentially make some 2x bruiser bot + a karma or lulu comp viable since it could actually end games. If this item had like 450 health and 55 armor, maybe it would see play, but at 300 health and 50 armor, it will remain unseen. Not to mention. it just got nerfed with a 50 gold cost increased? Yeah....
7. Thornmail: This item is honestly good, but is bad at the moment. Why? Because other armor items are bad. The only champion who can effectively use this item is malphite because he can actually get to a high armor count with his W passive. Maybe Garen as well, but less so. The fact other armor items have poor armor stats makes it bad since you won't get enough armor to make it do meaningful damage. It is also entirely useless against magic damage and to make it useful, you need to buy a frozen heart, which is also useless against magic damage, so unless you're against 4 ADs, you will rarely see this item be bought.
Finally, let's look at the health itemization. There are a couple of items who are pretty good, but some are pretty bad as well. On the good side, Steraks gage and Frozen mallet. The addition of jaurim's fist (BTW It's bugged and doesn't give health on kill, please fix) fixed the problem those items had, which is a awkward build path. The only problem I have with that item is that compared to phage, on purchase, it's a lot weaker in stats and doesn't have any utility for the same cost. It does make up for it overtime, but phage will remain a superior item on your first back compared to it. Steraks just allows bruisers to not get 100-0ed, which is a pretty big deal, but the bonus AD portion is a bit of an issue. Currently, it gives 25% bonus base AD. The problem is, it has 25 flat AD in it's build path. Most champions don't have enough base AD to even get 25 flat ad from steraks, or at least until level 18. This makes it feel like a damage downgrade on purchase as a early buy. The bonus base AD should really be 30% to make up for that.
Frozen mallet is actually extremely strong now. Again, the better build path is a huge part of it, but the fact it's insanely cheap and that it got it's stats left untouched for the most part makes it a really good bruiser item, since it gives you a big amount of health with a good amount of AD with the utility of slows. Compared to steraks, it has better stats, but it is a more offensive version of it and doesn't help you when getting bursted, so there is diversity in the departement of Health / AD items. There's even Titanic hydra for a damage item if you don't need the slow / anti burst, but the problem with titanic hydra is the same as thornmail in a way. It is very hard to stack pure health in this game because % HP damage and anti health items are pretty dominant, so you have to try to build hybrid health / resists items to make Titanic work. It's not a bad item, but it is hard to find a proper time to build it.
On the other hand, The black cleaver is actually a terrible item now. It got it's stats nerfed and it's cost increased, which confuses me. You might argue that 15 AD has more gold value than 100 health, and you are right in terms of gold effecienty, but not in terms of the purpose of the item. The item is meant to be for tanky champions who want's to stay alive for a long period of time so they can apply the shred on most people over the duration of the fight. The problem is, with the lack of defense it currently has, it is extremely hard to actually use the item effectively, since you get killed before you can actually make good use of it. The fact it has more damage doesn't matter because you can't use it. Also, 3500 gold is way too much expensive for the stats it gives. Combined with the fact the stats are poorly distributed now, the gold increase of the item made it pretty bad on bruisers. The item is almost getting forced into a assassin item when it isn't one, because you need time to fully apply the shred, so it's losing it's purpose. It should really get it's 100 health back if you're going to make it that expensive or just revert the change or make it cheaper in it's current state.
As for righteous glory, I don't know why the cost was increased, I felt like it was in a decent state at 2400g, being situationaly strong, but at 2600g, it feels a bit too much expensive. If you're going to make it 2600g, give it 50 or 100 health back at least to make it a bit more competitive with other tank items. In it's current state, Eye of the equinox and face of the mountain are actually better items for tanks in the jungle and the top lane than righteous glory since they are cheaper and have better stats while also having utility when those items are meant to be bought on supports.
The last item on the list is Warmog's armor. Sadly, this item sucks. It's too expensive and doesn't do anything other items would do. It's meant to be a tanky poke / infinite sustain health item, but it doesn't even do that properly. The health on it isn't good enough to buy it, since hybrid health / resists items like dead man's, visage and banshees have high enough health to be worth buying while also having resists to not get killed by % hp based damage. With the amount of % damage in the game, it is in a pretty bad spot. The health regen might seem nice, but items like visage, banshees and even zZ rot can do the same job. Steraks and Mallet also gives it competition since they both a good amount of health but also have a good purpose for bruisers with sticking power or anti burst while also giving you damage. If you seriously want people to buy this item, there's no avoiding it, it needs to be 1000 health again. The other health options are just strickly better that the extra 200-300 health doesn't mean much compared to the effects other items has.