tip: Satanic bible + mirror world + boss rush + the fool

with satanic bible you can take for free two devil deals items, the one given by the boss inside mirror world and the other on the outside of mirror world

to do this all you have to do is step on the white flame to become the lost, use the satanic bible and kill the boss, rinse and repeat on both mirror and normal

other tip extra is that you can "steal" one item from boss rush using the fool card after taking it, there will be always a fool card on moms foot floor on a x marked skull.

these two tips has won me so many runs.