Fallen skies, specifically. Is there an area/mob which has a higher chance of getting an item with it.
Pretty sure the only way to target farm something is for Monster Infrequents. You could sacrifice a goat to CRATE, but you’re probably better off expanding your farming goals. I accidentally got some of Kriegs set while farming for the Dark One set because I made pitstops in the cellar.
Heroes/Bosses+ always have higher chance of dropping items with rare prefix/suffixes, I suggest rogue dungeons or crucible.
Do crucible 151 - 170 + extra spawns with a fast farming character like dps infiltrator.
You’ll farm MI’s and legendaries much quicker than farming bosses in instances.
If you need to fill a specific slot and you’re happy with a basic green item rather than a specific MI (such as any green pant rather than those guardian pants you see in many top builds) you can try batch crafting basic magic stuff at any blacksmith (but Angrim is usually preferred). The sheer number of stuff you can create would improve your chances of getting the affix you want. It’s still just plain RNG and there’s absolutely no guarantee you would get what you want even if you crafted millions of items thought.