That is amazing about the magical house with all the rooms! And about merging into the matriss or walls.
My protective place is in a place like Narnia where I'm the warrior princess on a horse. I'm the protector of my inner child. I have a sword to defend against 'dragons" which represent my inner kid's fears. I also imagine taking my alters out in the state park behind my house to do survival skills. All this is very strengthening.