Considering helping out on the wiki to keep it updated - in particular the changed unique items need to be updated to reflect 2.6.0 changes.
Mods and base items have been updated to 2.6 values - skill progressions on some skill gem pages may need updating or some bugs need to be fixed.
A Perandus Coin is a currency item that could be used to trade for items offered by Cadiro Perandus. They were exclusive to the Perandus leagues. Now one can obtain and/or spend it only in maps opened with Perandus mod of Zana's map device.
Perandus Coins could only drop from Perandus chests, which appear only in maps opened with Perandus mod of Zana's map device.
In contrast to most other currency items, Perandus Coins have no inherent function for item crafting or other utility. However, in sufficient quantity they could be exchanged for items offered by Cadiro Perandus. Cadiro appears with a certain probability in maps opened with Perandus mod of Zana's map device. There is no another way to meet him.