Bloodborne Music Box Strat on Boss Father G

Equip the music box in your inventory and press square to use. Will cause the boss to go into a stun phase. Can be used multiple times. The music box is obtained from the crying girl in the lit window. Found after you've completed through the sewers. Every time you see him go into that stun phase pose is due to the use of the music box. Note, it seems you can only use it once during his transformed state. But in his human state it works multiple times as you can see.