I think the changes to abyssal mask and righteous glory re in the right direction.
As it stands tanks have very few options for mana sustain in lane, none of which are good against ap threats and the ones that are good against ad give 0 hp meaning they suck against hybrid damage and in early mixed damage skirmishes.
I think these new items will become the new core on many tanks in the next patch. I think malphite in particular loves the new abyssal mask, and I'm going to rush righteous glory on sion for a while.
There are only a few more things that could m be done.
1: Make adaptive helm not absolutely garbage. Buff it's damage reduction, make it apply teamwide, give it more magic resist or health. Any of those are decent changes. Also it's buildpath is pretty bad as well. Could do with a mr version of raptor cloak to combine with spectres cowl. (Think about all the other items that could build into as well)
2: Make sunfire cape not absolutely garbage. No one really buys this item anymore, because it gives tanks more of what they already have. Try increasing the radius based on model size first, and rebuffing its damage a bit.
3: Increase the resists on all items that exclusively provide resists without hp. These items got inadvertently shafted due to the increase in resists overall making them less good as purchases. Try adding 10 total resists to these items to make them better.
That would be all I have to complain about here, but as it turns out the bois (& grulls) at riot are steadily returning tank itemization to its previous levels of diversity while also introducing excellent core items. Good job!