Undecember craft and mod tier

ILevel 139 - meaning it cannot roll T12 for some mods (minimum requirement is 141). And even if you do hit your godroll multi T12, its going to take a shitload of crafting mats to do it, as your chances are low because of the item level.

ILevel 141 minimum tier is T5, 144 minimum tier is T6, 145 minimum tier is T7. 

[Source]