Sets the Devil Room chance to 100% regardless of all other modifiers, guaranteeing a Devil Room or Angel Room Door will spawn whenever possible and remain open.
Notes
Even if taken after a boss is killed, Goat Head will force a Devil / Angel Room door to spawn on that floor.
Taking a deal with the Devil will prevent Angel Rooms from appearing, meaning Goat Head must be acquired from another source for an Angel Room to spawn.
Goat Head will not force a Devil / Angel Room door to open if the boss fight was in a narrow room.
Goat Head has no effect in Greed mode and is not normally available.
By touching the white fire in Downpour II and Dross II, Isaac will temporarily become The Lost. After defeating the boss, Goat Head will always keep the devil deal door open, allowing the Lost to take one Devil Deal item for free.