Destiny 2‘s The Witch Queen expansion brought with it a new six-man activity called Wellspring, which takes place after the story events in the main campaign. The Vanguard and the Lucent Hive are fighting for control of Savathûn’s Wellspring in a cycle of offense and defense. This activity has a unique loot pool, meaning some weapons in the game only come from that activity.
To emphasize the back-and-forth nature of the fight between the Lucent Hive and the guardians, there are two variants of the Wellspring activity—Wellspring: Attack and Wellspring: Defense. These rotate every day, and they determine the rewards that can drop at the end of each activity.
Each day, one designated weapon will drop from Wellspring missions, similar to Altars of Sorrow on the Moon. For that day, Wellspring completions have a chance of dropping that specific loot, as well as other legendaries or Throne World armor.
Father’s Sins is only on rotation in Wellspring: Attack, dividing its time in the spotlight with Come To Pass. This means Father’s Sins isn’t available permanently and players must wait until it lines up with the reward schedule.
In addition to Father’s Sins, players can also get the Come To Pass auto rifle, the Tarnation grenade launcher, and the Fel Taradiddle bow from Wellspring completions whenever they’re the designated reward. They are craftable, but unlocking their Pattern requires completing several Deepsight Resonance objectives with each weapon and may not be within reach for most players.
Players can check the Wellspring rewards by hovering their mouse over the Wellspring node in the Throne World or over the mission title during the launch screen. This will allow you to know exactly which weapon is on rotation and to prepare for what will drop.