Complete a few quests obtained from Petra and collect Tech Witch Brooch, and you will get the Boolean Gemini, a new Exotic Scout Rifle included in Destiny: The Taken King. To have a better chance to put your hands on it, anyway, be sure you read our guide's tips below.
Basically you will have to do three quests from Petra, caring about a couple of details that will fasten up your road to the exotic scout rifle. Here you have them:
Step 1:
Complete the Queen quest The Taken War: Petra. The quest will send you on different planets and ask you to kill Taken Champions. You need to fight and kill Fallen Lieutenants to summon Taken Champions.
Step 2:
Complete the Wolves of Mars quest. Find a friend to help: this mission is for 40+ level.
Step 3:
Complete Lost and Found. This involves patrolling the Dreadnaught and killing various enemies at three destinations in the Dreadnaught – the Mausoleum, Hall of Souls, and Hull Breach. Then, at the Court of Oryx kill bosses until you get the Tech Witch Brooch.
Finally, go to Petra and obtain your deserved weapon.