Azazel
ReadyMake 3 deals with the Devil in one run.
Achievement
Defeat Mother as Azazel.
In-game: “Complete the Corpse with Azazel.”
Sources:AchievementsMotherCorpse
Make 3 deals with the Devil in one run.
Defeat Mom.
Reach Depths II and defeat Mom.
Sources:AchievementsWomb
Defeat Mom's Heart 10 times.
After: The Womb
Defeat Hush 3 times.
After: The Womb, Blue Womb
Defeat Mother as Azazel.
After: Azazel, A Secret Exit