When they do the cabal raid, it needs to be a war. Their largest fleet ship invades the city and all guardians are responsible for it's defense. There are no fireteams, but there's a new open world map called "the city" that supports up to 64 players. There is no minimum level but lesser players will likely die. Your goal is to make your way through the legions of cabal and invade their ship and kill the cabal leaders. Only then will everyone on the map be granted loot. The loot resets every day, but the battle is incredibly long. It takes 10 hours to make it all the way through the ship. Whichever guardian manages to kill the final boss gets additional special rewards. Now THAT'S how to become legend.