I wrote this explanation a while back for another post and saved it, glad I did. And from unique monsters and minions from area level 80.īelow that level, there is no path from the individual monster TC to the TC87 item. To answer your specific question though, TC87 base items start dropping from normal monsters in areas with level 83. And TC 87 bases are rare because very few paths lead there. For example Sigon pieces are quite common because a lot of paths lead towards the base items. In one sense, the individual odds are also given by the relationships between TCs in the web.

This image here conveys the intricate relationships: Treasure classes form a web, with one treasure class referencing one or more other treasure classes, and it, in turn, being referenced by one or more treasure classes. And not everything is tied to area level, though in most cases that is true. There are 800+ treasure classes in the game. Your findings are correct, and you're right, the answer 'only level 85 areas' is wrong.

Diablo 2 treasure class