I just got spectre mask. It's rare. took me about 4-5 hunters to get it but it's possible.
https://imgur.com/a/wprsBvt
Just killed Death and his gang and he didn't drop his. Just some high-end bs. Can we get some response from the devs on this? Aren't these supposed to be 100% drop chance? How am I supposed to get this when you can't refight them? Come to think of it, none of those you dropped an Ivory Key. You didn't do something dumb like tie his drops to a location, did you? Because that last one (Death) ran all the way up the steps of a building across the street before we killed him.
Edit: found out what was going on. In the Hunter encounter at the Christmas tree there are actually 5 hunters, not 4. One of them doesn't drop a mask, but you won't get the key until the fifth dies. I was able to retrigger the encounter and finish it, but somehow during my first encounter Death just straight up wandered off and vanished. That's the only explanation I can come up with since after killing the fourth and not getting the mask I went back to the tree to see if I missed it and there wasn't anything around. Maybe he had just wandered too far, but I also suspect he straight up despawned himself due to the distance the fourth hunter had created between us..