Scarlet Chest is an unlockable pickup in Repentance Plus, a mod for The Binding of Isaac.
Requires means of accessing Red Rooms to open:
• Opening the chest with a fully charged Red Key discharges the item.
• Opening the chest with a Cracked Key removes the consumable.
• Using Soul of Cain opens all Scarlet Chests in the room.
• Opening the chest with a Crystal Key has a chance to 'jam' it, making Isaac no longer able to open that chest with the trinket. The chance to actually open the chest is the same as opening the Red Room (33%, 50%, and 100% for 1, 2, 3 trinket multiplier). 'Jamming' the chest drops a normal room clear reward.
Possible drops
• 66% - Random item from the Ultra Secret Room pool.
• 22% - 1-2 reversed tarot cards.
• 11% - 5-15 keys.
Enter an Ultra Secret Room 3 times.