Archievement Dream Corruption

I am trying to get the "Dream Corruption" archievement,
so I have to use a vaal orb on T15 maps (like Sunken city
or Carcass map) and hope for the correct outcome, right?

Does somebody know how rare it is to get a Vaal Temple map
out of it?
Or are there other ways than that which are easier?

Would love some help.

If I'm understanding the mechanics of a Vaal Orb correctly, you should have a 1 in 4 chance of getting a Vaal Temple map.

There are 4 possibilities when using a Vaal Orb on a map:
1) Nothing happens beyond the "corrupted" tag being added
2) Map turns unidentified with same mods
3) Rerolls map affixes
4) Transformed into a higher-tier map (aka Vaal Temple)

Thank you very much for your explanation!

I haven't been lucky on my first maps, I guess
I'll have to keep trying some more. :)

there are several possibilitys but they are surely weighted, getting a +1 is way less common then others

dont forget 8mod is also a possibility

It just happened! <3

Took about 25 maps to make it happen
and I am very happy now :)