I got this in “The Choking Grounds”. When you first go there, the giant stone golem will ask for you to lift the curse, you have to go to four portals and do various tasks. At one of them you have to kill 40 enemies. You will know you are in the right one because a lot of zombies will be on the ground. First thing they do not mass huddle around you. If it’s not upgraded, you will only get five or six. What I did was run into a corner turned around and a lot had grouped up, so I dashed out and used the Blade Geyser when I hit the middle, getting 16 kills. You can make a save before this, but it will auto save just outside the portal.