Giant House is a secret boss in BLACKSOULS 2 you can find in the secret area called Backyard, located in the Mushroom Village.
To get to him you have to go all the way northeast until you reach a big house, then make sure you have 0 SEN and the house will be gone, allowing you to go further into the area.
This will lead to the Backyard, and behind the fog will be the Giant House boss fight.
On the sign before the fog, it says “BLACK RABBIT” which is referencing the Prayer Master. When you defeat the boss you will see the Prayer Master’s grave – the Carpenter built this house and this grave for him.
Go to the Jack-in-the-Box and trade Soul of the Giant’s Home for the Black Rabbit Ring – this ring will give you a 100% Bonus Action Chance.
