Hunter's Cape

I'm not having any luck searching.

I'm trying to get the Hunter's Cape, and according to the wiki, it drops from an NPC when killed. The problem is, the NPC seems to be coded vital - he's immortal. I don't want to say the name, in case it's a spoiler (I'm still in Act 1) but here's the link.

https://taintedgrail.wiki.gg/wiki/Hunter%27s_Cape

Is there something I'm missing? Is the wiki out of date, or perhaps the NPC becomes killable later after a quest?

Thanks in advance!