Saint-14 has arrived at the Tower in Destiny 2. You’ll need to complete the Completing an Impossible Task quest for Osiris if you want him to show up during Season of Dawn, so make sure you’ve done this first. After, you can find him in the tower next to his ship in the hanger. It’ll be difficult to miss him. When you speak to him, he’ll have three quests available on him, and this is one of them you can do.
Step 1: Community Service. Saint-14 wants to start helping out the residents of the Tower by helping them complete specific tasks. For this step, you need to grab eight bounties and have them completed. These need to be Gambit, Crucible, or Vanguard bounties, so make sure you speak to The Drifter, Shaxx, or Zavala to complete any of these.
Step 2: A Sense of Duty. Once you have completed your shown bounties, you must return to Saint-14 in the tower to tell him of your acts.
Step 3: New Duties. Now that Saint-14 has had a taste of what things can happen on the Tower, he’d like to add more tasks for you to do. Place the new bounty book on the stand next to his ship. By unlocking this, you’ll gain further access to opening the Obelisk on the tower.