staffofbuilding-1.0.0_20w19a.jar is a release file of the Minecraft mod Staff of Building for Fabric, made for Minecraft 1.16-Snapshot. It was published on May 18, 2020 and is 0 MB in size. For the full description, screenshots and every other version, visit the Staff of Building mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.