725 (on Mausoleum)
- Pops out of the ground near the player 3 times and throws 5 bones each time.
- Summons waves of spikes in the cardinal directions.
- Charges towards the player at high speed. Upon colliding with a wall, bone projectiles and rock waves are sent in all directions.
- Spawns Bonies.
- The Pile is a posthumous form of Polycephalus, similar to The Stain added in Afterbirth.
- Despite the fact that The Stain was already in the game, the Pile was also added into Repentance, meaning Polycephalus has two posthumous forms.
- A third skull can be seen in the background of The Pile's boss art.
- Antibirth's artist, NotYourSagittarius, first posted a versus screen of this boss and then a full mockup in the Isaac subreddit both in January 2015, which was implemented by antibirth's developer Kilburn into a mod during the same month.