Vendoring 3x maps will yield a map of +1 tier. Before watchstones update (atlas change in 3.9) the result was always a single predefined map. Now it's one of many maps and I am trying to figure out the rules.
I've found this helpful spreadsheet, to example, selling 3x T1 Warf maps may yield one of following up T2 maps:
- Alleyways
- Cursed Crypt
- Laboratory
- Strand
Let's say I need Cursed Crypt map. How do I get it?
I figured out it's a function from item unique ID.
Currently I am putting all Warf maps in my inventory. To example I have 5 maps and I am putting them like on screenshot below and then I am trying to sell 3 of them by control-clicking map in inventory (always from top to bottom):
which can be seen as binary bits: 11100. So I am trying all unordered combinations possible, with following real outcome:
11100 -> Laboratory
11010 -> Strand
11001 -> Laboratory
10110 -> Strand
10101 -> Alleyways
10011 -> Alleyways
How do I get Cursed Crypt map. Do I miss some other parameter of that function?
Best Answer
The vendor recipes are not documented officially, but you can find information on them in the community-maintained wiki on this page:
PoE Wiki/Vendor Recipe System
After 3.5.0, the outcome of the recipe became randomized. There is no guarantee to get any particular map, and there is no mention anywhere that the function is total.
In fact, the spreadsheet you provided gives multiple tiers with more than six maps. If you happen to have three Tier 10 Wharf maps, you can combine them in six different ways (3*2*1), but there are eight possible outcomes. This shows that totality is impossible. it is even worse for other tiers (T14 has 13 possible outcomes, more then twice the number of combinations available).
Your assumption that you can get every map from a higher tier with an arbitrary combination of three of one map in a lower tier is unfounded.
So to answer your question:
Get another Wharf map and combine it with all possible combinations of two of the three maps you already have.