A question about some altars

Nobody can tell me what kind of altars these are, as I understand it they should be related to the seasonal mechanics and give the opportunity to make stones for jewelry, but I’m already at T3 and have never seen any altars. Does anyone know how to understand this?

They are very rare.

And the “only” thing you can get from them are the so called lost witch powers. Like Piranhado for example.

Or you reffering to the 2 week event shrines, these are the purple shrine thingies on the minimap.
There you can get reputation to get some stuff in Ked Bardu.
Activate the shrine and kill monsters in the time, the effect last.

Oh no.
I wanted to make a stone for an amulet but noticed that to make it you need some kind of shrine, and I’ve never found one anywhere. Well, I don’t think it should be that rare, I suspect that it’s disabled because I didn’t want to take VoH.
By the way, I also encountered the inability to see how many of what materials I have and which ones are required, and everyone has the same icons. I don’t understand who screwed up with this either.

The stones for the amulets you can craft at Galena (i think it is her name).
You can right click on a stones there, so you can switch between description and cost.

For the blue ones, you need fragments, a fugitive head and rot. The last 2 are new in this season.