I got them before 0.8.3. It’s a random drop so farming any zone above the minimum level would do. Higher corruption (-> higher increased rarity) will give you more uniques so more chances of it dropping.
Unless you are a diehard item chaser and have the mental stamina to run hundreds (if not thousands) of maps over and over looking for a totally random world item, I recommend that you dont… the RNGods & Murphy will see you coming a mile away and no one wants to let those f$%#$@s get hold of you…
After about 1k playtime I have realised that LE has more than enough to interest a player into just playing the game and over time those juicy build defining items DO eventually drop… Sure, sometimes I will run a few hundred maps looking for a Bastion of Honour but I have learnt to just play and when a chase item drops - then and only then do i try out a build that requires it…
So… for diehard item chasers - go for it… for the rest of us… just play…
I have one omnividence staff, dropped randomly somewhere about a month ago I think, I know it was normal mono, but I don’t remember more.
And three days ago I dropped an orian amulet(I’m very pleased, I’ve been wanting it for my mage for a long time), also normal mono, and with a very small magic find.(I almost missed it, I was playing void warpath and my echo killed the mob and I just saw the uniq drop icon on the minimap, I didn’t even want to go back but I went back to the drop spot and there was the orian haha)
So RNG is really erratic haha.