The Arch-Archer's Catacomb is a tiny building that rarely generates in Taiga (snowy tree) biomes. This will have the "Arch-Archer" within, wich is basically a skeleton with 4 arms and 4 bows that will rapid-fire arrows at you. Once you enter the building, you step on pressure plates (that actually have nothing to do with the Archer appearing, you could destroy them but he'd still appear). He shoots arrows at a very fast rate. (2/sec) The Catacomb will always be either White or Gray.