Cain
ReadyHold 55 coins at the same time.
Achievement
Unlock Tainted Cain.
In-game: “Unlocked challenge #43.”
Hold 55 coins at the same time.
Defeat Mom.
Reach Depths II and defeat Mom.
Sources:AchievementsWomb
Defeat Mom's Heart 10 times.
After: The Womb
Defeat Isaac 5 times.
After: The Womb
Defeat Hush 3 times.
After: The Womb, Blue Womb
Defeat Mother.
After: A Secret Exit
Open the hidden closet in Home as Cain.
After: Cain, The Polaroid, A Strange Door
Unlock Tainted Cain.
After: The Hoarder