Now before you rage at me cause you PVE justice heroes are fond of doing that, hear me out. If you think about it, it kinda does.. other than stat changing and the "Stylish and prestigious" look that Legendary armor gives you. It's functions would have the same as legendary armor. Although i do believe this function should've been added with the Legendary armor too cause that rune swapping can get tedious and tiring after awhile. But the Build template implementation would basically just be doing the same thing legendary armor could do just using more armor sets / runes/ sigils / ammy's / rings.