I've spend hours in one sitting doing the first 2 encounter of duality solo, couldnt complete the final boss had to take a break after about 4 hours playing non stop, play the next day from the checkpoint and completed it after 1 and half hours and the triumph to 'complete all duality encounters solo' didn't pop up after all my hard work, my fireteam was on closed the whole time and nobody joined. Hours of hard work for nothing:( I guess because it wasn't all in one sitting but that's so dumb I'm not the best player and to get that all in one sitting is so annoying after hours of hard work I don't have my triumph:(