Borderlands Pre Sequel. Athena vs Invincible Sentinel, Longnail Drops

The mission "The Bestest Story Ever Told" allows the player to take on the Sentinel again in its Invincible version after paying 20 moonstones. The Invincible Sentinel is a lot harder as you would expect and the Longnail drops first time. Even if it is only the fire version of the gun. Skip to 24.00 to see the loot search.