Can confirm. I got a Hallowed Key Mold in my farm before the Rod of Discord. I finally got one a few minutes after that.RoD. I've killed thousands of Chaos Elementals and no luck, until very recently.
It is literally the rarest item in the game, so you need a lot of luck to be able to get it.Slime Staff....I've spent atleast an hour at the grinder and NOTHING!