Did it today... And it is basically the Crota fight. Kill Swordbearer, dps Crota, and sword him while he kneels. Much more intense than the Crota fight, since you don't have the space that you do in the Crota fight, and there are plenty of adds as well. I tried using my heavy sword, but he is immune even when kneeling. It's the most fun that I have had in this game yet. Without gally as a real option, weapon choices are a little limited. I used a blue 290 heavy, and my bro had weapons of light and hit him with rockets and sniper. When he started to kneel, I shot him with shadow shot, and everyone but the sword guardian had to focus on adds and get their weapons reloaded for the next down. Took 2 swords of I remember correctly. The bubble made it possible. Without it, the dps just wasn't enough to kneel him quick enough before I emptied my magazine. It also have shelter to reload. I assume that tier 3 will rotate every week... I really want to do that again. Took us 2 tries, first was exploratory, when I tried my sword as well. Died every time I tried.