Well....other people may need to know this, but I will point out that I left the public dungeon, and the delve, killed the first tiger I saw and the lead dropped. So.....

im pretty sure that delves/public dungeon count as different "zones" for all intents and purpose, and there are some leads that specify they drop from a boss in a delve

so for lead that comes from malabal tor enemies, it has to be in the overland area (i got the lead from a dolmen boss mob lol)

So I decided I need to get the Oakensoul so I started the effort to acquire the leads. There is a good bit of information available if you google these days so everything was pretty straightforward, except this sacred resin lead. The first reference I googled said that it would drop from any mob in Velyn Harbor Tavern in Malabal Tor. So I spent about 10 minutes killing every human mob I could find in Velyn Harbor including at the Tavern and no drop. Then I went to another website that said any mob in Malabal Tor and had the Public Dungeon and Delve kinda circled on a map. Making me think that possibly I could get it there. So I went and spent time in the Public Dungeon, the Delve, paying particular attention to non-human Ogres and Tigers/Snakes....but nothing. Then I went and did a Dolomen and got a lead drop, but not this lead. Then I went and did two World Bosses and got another lead, but not this one. So after about I dunno an hour and a half...still no lead. So I'm thinking that the other posts are key in that I'll bet the lead drops from non-human mobs like Tigers/Wolves/Mudcrabs/maybe snakes/Spiders/Assassin Beatles, etc. Just not human mobs. I'll have to try being cruel to all the creatures in Malabal Tor to see if I can finally get it.

I think you may undoubtedly be right about that. When I log on this evening I may try that angle...as it seems the harder you search or try the longer harder anything is to obtain. Had that problem with overland sets when farming....seems that if you wanted it, the items just would not drop. Then later when you already had the set...in passing you'd get four or five of the things you couldn't get your hands on before. Truly frustrating at times.

But I do think that the general rule is that this Sacred Resin Lead drops more from monsters/animals in Malabal Tor and not as much humans/daedra and only in overland and not public dungeons or delves. Unsure if certain parts of Malabal Tor are better than others, but from what I've gathered seems like the upper right Velyn Harbor and middle portion of the coast line is best place to start.