3rd Phase - He is out of reinforcements. 6 vs 1 showdown. He has a shoulder mounted rocket launcher and minigun like War Machine. As well as a massive 2 handed battle mace/hammer. Players at this point can pick up discarded Phalanx shields lying around. The mechanic operates like the relic/sword and goes to third person. You have a shield bash attack as well as a block where you duck behind the shield. You may only use sidearms or handcannons in this phase. He has a shield that cannot be damaged until players destroy power sources setup around the roof. Once his shield drops, players can take out his shoulder mounted cannons so he can only melee. You must block his melee using your shield function or it's a 1 hit kill. For every Guardian he kills he gets bloodlust buff that stacks and he moves faster and attacks quicker. Eventually you will burn him down. As he lays there dying he starts laughing looking up to see his success. Loot rewards. End mission 30 second timer starts. As soon as you finish killing Legatus Tha'aull, he lets you know how futile was as he already activated it once he knew you were on board, Watchmen style, and the last thing he sees is the sky open up and the sky is blacked out by Cabal warships like the last story mission in HoW, and you see a ship come closer and a portion of it opens to reveal a Cabal figure in epic futuristic armor staring down at you. It's the Cabal Emperor. The Exo Stranger then appears briefly to teleport you back to Earth outside the city as you see flames and smoke rise up and more Cabal ships while the city is being bombed.