It would be great to see a return of those shrines that used to appear from time to time in rare locations or in the place of explorables that would allow spellcasters to alter their permanent summoning theme.
I feel like a pilgrimage to the heart of each of the planar rifts to acquire a specific elemental attunement at a shrine deep within would be great and would also be an enabler of some great RP for example, but some rarer themes popping up from time to time, or maybe randomly in the Wizard Warrens would be great to see too. And as usual, the number of times one might alter their permanent summoning theme in this way may be restricted.
Challenging some manner of quest in each elemental seam that has a shrine at the end of it is something that sounds quite wonderful. Or even perhaps hidden areas in explorables found in these seams?