So for Vaal Temple my thoughts on what could change a bit.

My thoughts on Vaal Temple.

What I would like to see be changed is simple, the way you access it for one should be changed to allow it to be more common for access.

So when you come across the summon spots, what I think should happen is simple, it summons guards of the temple to fight be it that boss or the guard pack or wave.
Kill them they drop a power core stone at the end which allows you to access the temple door like the other content that already does this.

Which these power stone then can be traded, in the same way that others can be an would fit with the theme of the Vaal as well.

Also Make it so the boss has a chance to summon at any time higher % chance based on higher level map tiers, but once you hit say the 6 time its always 100% appear fight for the boss always.

I also kind of would like to see the rewards for the temple slightly buffed as well as it kind of so so atm.

Thats my thoughts on the Vaal Temple.

Edit- Added my thoughts to the power stone cores- can make it effect how many added rooms you get.

So like this, the base drop could be Medium power stone would be the same level access currently.
Large power stone which drop's from the boss could give 3-6 extra floor rooms.