Wait so I heard something about a "15% defence buff in super" when using full masterwork armor, but most if not all use an exotic in tandem with their armor set, rendering the buff useless.
Ignore if this isn't a thing.
15% is the maximum. Each piece grants 3%. If you have 1 exotic, you get.... 12%. To be fair this should be better explained in ingame tooltips. Shouldnt have to go on a forum to find out whats going on in the game.