Perfection is a trinket. It drops from a floor boss every three floors without taking damage, and cannot be found through other means. It will continue to be dropped by every subsequent floor boss if damage is still not taken.
Perfection can be dropped manually to prevent destruction before knowingly taking damage.
Perfection can drop multiple times. However, only one can be held, even with Mom's Purse.
Getting shocked by the Charge Machine will count as damage and will destroy Perfection.
If the Lost has additional lives and dies, Perfection will get destroyed because it counts as damage.
If you complete the first floor without taking damage, but proceed to do all of Downpour without taking damage right after, the boss will not drop Perfection. Completing either Mines or Caves will then cause the boss to drop it.
This means that if you intend to do the full alt path, you can take damage on the first floor because you can't get Perfection on Downpour 2 anyways.
Blood Oath: Counts as damage, destroying Perfection. You can't protect Perfection by dropping it since Blood Oath stabs faster. The only way to keep Perfection is by quickly leaving the starting room, which requires a lot of speed.
Voodoo Pin: Counts as damage and will destroy Perfection. However, Perfection will spawn again once the next boss is defeated (unless actual damage is taken before that).
Bug! If you complete the first floor without taking damage, but proceed to do all of Downpour without taking damage right after, the boss will not drop Perfection. Completing either Mines or Caves will then cause the boss to drop it.