The Yellow Demon's Soul is a consumable item in Demon's Souls.
It radiates a strong power…
Grants the holder a large number of Souls when used.
Alternatively, it can be made into spells, miracles, or weapons.
Dropped by the boss Old Monk.
The Yellow Demon's Soul can be used to ascend a Wooden Catalyst or Silver Catalyst into the Insanity Catalyst with Blacksmith Ed.
It can also be used to purchase the spell Homing Soul Arrow from Sage Freke, the spell Soul Thirst from Yuria the Witch, or the miracle Banish from Saint Urbain.
It can also be consumed for 26,400 souls.