Always use it on the first floor of a chapter to be safe. If they drop Cube of Meat, restart and try again. The Harbingers are necessary as they always drop either Cube of Meat or Ball of Bandages. Whenever you use the Book of Revelations, it forces one of the bosses for the current chapter to be one of the four Harbinger bosses.

The easiest way to do this is to restart your run until you get the Book of Revelation in either the Item Room or a Library. Balls of Bandages can only be found by defeating a Harbinger boss (Famine, Pestilence, War and Death). Something Sticky - Beat Chapter 3 20 timesДЄ Bandage - Make a Super Bandage Girl by collecting 4 Balls of Bandages. Something from the Future - Beat The Basement 40 times Loki's Horns - Defeat Lokii for the first time Lil' Chubby - Beat Chapter 2 for the first time Monstro's Tooth - Beat Chapter 1 for the first time The Harbingers - Defeat Mom for the first timeДЄ Cube of Meat - Defeat Mom for the first timeД«ook of Revelations - Defeat a Harbinger for the first timeДЄ Fetus in a Jar - Defeat Mom's Heart 9 times Magdalene - Have 7 or more red heart containers at once

I won't go into great detail unless it is necessary and not explained elsewhere. A lot of these will likely be repeated on other pages as they are also tied to some achievements. As of Afterbirth+ there are 178 and all are needed for PG, RPG and 1001%. Secrets are essentially in-game achievements. Ending 16 - Unlocked by defeating Mega Satan for the first time.Д®nding 17 (Afterbirth) - Unlocked by defeating Hush for the first time.Д®nding 18 (Afterbirth) - Unlocked by defeating Ultra Greed in Greed Mode for the first time.Д®nding 19 (Afterbirth+) - Unlocked by defeating Ultra Greed in Greedier Mode for the first time.ДЇinal Ending (Afterbirth+) - Unlocked by defeating Delirium for the first time.

The binding of isaac completion marks