Stag Antlers allow you to upgrade your gear and certain weapons in No Rest for the Wicked. But obtaining Stag Antlers is a lot harder than it seems.
Beat Every Boss Easily with Parry in No Rest for the Wicked
Increasing the quality of your offensive and defensive items is a non-negotiable for reaching No Rest for the Wicked. This will allow you to defeat bosses like Warrick and Darak, in addition to other useful tactics like leveling up the best stats.
Having the right materials and resources is important in the upgrading process. As you unlock more of the best weapons in No Rest for the Wicked, you will need rarer resources, such as Stag Antlers.
Deer antlers appear to be a completely random drop in No Rest for the Wicked for now, and can only be obtained from chests, vendors, and as loot.