Swordbearer. A place with three walls is either a triangle or open on one side. Like the Crota room. And dealing my dealings as one glided across the u shaped. Crota's pattern is a U shape. Also has three spots that he stands or three areas you see the target but you only use the sword against him when he's in the middle. Three floors? I suppose the ground level where ogres spawn, the level with the crystal and Crota and the level with boomers. As soon as you pinch the sword bearer and a gaurdian is able to use it to kill Crota, you tear apart the reality of the Hive's world by destroying the soul of their god.