"We want defensive item purchases to be reactive" - Warden's Mail should build out of Chain Vest
From the Preseason promo site:
We want defensive item purchases to be reactive to the situation, and also not trap players into buying items they don't want, so we've simplified a number of build paths by adding lower-cost components. For example, Chain Vest now builds out of Cloth Armor.
It's not something of top priority, but it matters when you have to decide between Randuin's Omen and Sunfire Cape (already made the mistake of buying Chain Vest once :D ). Buying resistances was supposed to be easier, but with Chain Vest no longer being the "This builds into big armor" item you lose out on flexibility (build big armor first, adapt the final item to the situation later), and Chain Vest lacks any identity compared to other Cloth upgrades, if compared to Warden's Mail and Glacial Shroud as a parallel option.
Example changelog:
+
750g
1100g (+50)
That's not even the only issue with armor items - ever since the change to Glacial Shroud (which was good, though) Iceborn Gauntlet has been a very situational luxury item for tanks, rather purchased on mana-demanding champion such as Ezreal, Blitzcrank, and AP toplaners like Kassadin and Gragas. The item was introduced as a "tank upgrade of Sheen", but it's not in a good place for tanks - it's the most expensive armor item in the game, aside from Zhonyas, and it has only 20 out of 60 armor in its components. You have to sit on a very small amount of armor until you complete whole the thing.
Last armor throw-in is a suggested change to Thornmail build path - Rammus aside, this is a reactionary item, not a power item. I don't think it deserves such a high combine cost and it could go down by a small amount.
+
+ 100g =
3000g (+100) - possibly bundled with bringing its armor back to 70
2200g (+100)
As for Magic Resistance, the only problem here would be high combine costs for 
Guardian Angel (1500) and 
Banshee's Veil (1150). Both are often used as the "survi" item by AD Carries, and with upcoming reintroduction of Negatron Cloak GA should be fine - but Banshee is also utilized by tanks, for whom it's the item with highest existing combine cost at the moment, now that Omen and Sunfire got cheaper. It's worth noting that BV took also a significant hit to its health regen - from flat 45 to 100% (effectively 10-20), although now it works outside of combat as well. A good way to turn down that nerf a little while not bringing back the 5 Banshee lineups would be introducing Crystalline Bracer to Banshee's recipe:
+
+ 950g =
+ 800g =
while we're at it.
Generally Crystalline Bracer could help smooth out buildpaths or outright rebalance few items that are supposed to work better on tanks than on fighters, due to the nature of % base regen - for example, if Juggernaut turns out to be a bit too strong on towerdiving bruisers, it's possible to trade 50-100 health on it for the health regen, which tanks would appreciate a lot.
Back to the premise, though. Chain Vest should build into Warden's Mail. Why not, anyway?
