Corrupted Areas and map

I would make corrupted areas spawn in maps if a Vaal Orb is used on the map (so iff the map is corrupted).

It could be a fixed % (non minuscule, like 10-20%) or a fraction of the total quantity; for example quantity / 5 so at 100% qty you'll have a 20% chance of having a corrupted area.

This change might ease the need of finding weird ways to farm for corrutped areas and it'll integrate the search in the current end game mechanics.