Dad's Key

Dad's Key is an unlockable activated item.

Effect[ | ]

Upon activation, opens all doors in the current room in almost all circumstances.

Any normal doors that are closed during combat, even on floors that normally disallow this;
Any dоor requiring Keys;
Any door requiring Bombs to blow open (including Secret Room and Super Secret Room doors);
Challenge Room and Boss Challenge Room doors regardless of health total;
The door to the Mega Satan arena;
The Boss Rush door from inside;
The doors of a Mini-Boss Room from inside;
Most Boss Room dоors from inside;
The Mausoleum / Gehenna doors without paying the health cost.

The Boss Rush door if the timer has already passed 20 minutes;
The door to the room leading to ??? if the timer has already passed 30 minutes;
Angel Room or Devil Room doors;
Locked Chests of any kind, or Key Blоcks;
The door of Mom's Boss Room from inside;
The exit door in Greed mode;
- Leaving the main room before clearing a set of waves will reset your wave counter, and repeated waves will not drop coins or charge your activated item.
The door to The Void during the Hush boss fight;
The flesh door leading to Corpse;
A Strange Door.

Book of Virtues: Creates wisps in the middle ring. If the wisps touch Locked Chests, Special Room doors, or uncleared room doors, they will unlock and open them, destroying themselves in the process. These wisps can open any locked door they touch, including the door to the Mega Satan arena, A Strange Door, and the flesh door to Corpse. Bomb Chests and Mega Chests are unaffected. They will also donate to Key Masters on touch, destroying themselves in the process. Opening a chest in a Challenge Room with a wisp will not start the challenge.

This item is used in The Family Man (challenge #19) and Red Redemption (challenge #44).
Dad's Key may be a reference to Isaac's father leaving his mother, as it can be used to escape from almost any conflict.
In Wrath of the Lamb, this item was unlocked by beating ??? for the first time.