I never chanced anything before, mostly because I don't like to gamble; Usually just save up my chance orbs and sell them in bulk for exalts. There has been several post on reddit(just screen shots, no one has gotten a video recording of league specific being chanced), but nevertheless it was very interesting and someone needed to provide concrete evidence without a shadow of a doubt that, you could in fact chance those uniques. Now, I gotten pretty lucky this league with a Shavronne's wrapping drop + kaom's heart(which isn't worth much this league) + countless Exalts, So I have quite a huge bank toward the end of the rampage league. So I decided, "hey! it's time to burn all the currency since i'm strictly a league player."
I decided to dump all my currency into Chance orbs and Scouring Orbs. Since I don't see anyone else with a headhunter on Rampage and it is just such a fun unique, so why not be that one guy who has that one belt that everyone wants? At the same time, I really wanted to get some up to date data on the chance of chancing any unique that the PoE community can use. (FOR SCIENCE!)
So a few full tab of chance orb/scour orbs later. I started chance/scouring away.
Now, In order to chance these league specific uniques You NEED to be using the Zana's map mod related to that league. On top of that Chance/Scouring must be done IN the map.
You CAN bring the base item into the map and chance it# However I was super paranoid so I decided to only use leather belts droped in the map.
*Watch the video to see all the unique belts I chanced.
Total chance/scouring attempt:
Spoiler
1369
So possibly 1 out of every 200-250 are uniques (more likely lower tiered uniques of course)
6 unique out of 1369 = 0.44% chance of a unique
results:
Spoiler
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Still got some thousands of scouring/Chance left(might as well keep chance/scouring for more data) I'm going to start a straw post on the next unique you guys want me to chance.