Weapons upgraded with Petrified Dragon Bones gain 30% physical damage per upgrade and can be upgraded up to +5 for a maximum bonus of 150% physical damage (×2.5 base physical damage). Overall, it takes a total of 15 Petrified Dragon Bones to fully upgrade a weapon that was created using a boss soul.
- In a cell to the right of Straid of Olaphis in the Lost Bastille. The Bastille Key is required to unlock the cell.
- Iron Keep, in the furnace next to the Smelter Demon boss room. The furnace must be turned off by activating a valve located near the top of the external wall.
- Aldia's Keep:
- On the ground, past the King's Gate and before the Foregarden bonfire.
- On a corpse in the main hall, in the area with many mirrors on the wall from which blue phantoms break out.
- On a corpse in a corner of the pool of yellow corrosive liquid down the stairs from the Ritual Site bonfire.
- Drops from Dragon Acolytes.
- Shaded Woods, inside the chest located one level above the Shaded Ruins bonfire and across the gap from the Giant Basilisk.
- Drops from the Giant Basilisk in the Shaded Woods.
- Trading with Dyna and Tillo:
- Drops from certain Crystal Lizards in Brightstone Cove Tseldora and Dragon Aerie.
- Purchase from Stone Trader Chloanne for 17,500 souls (only 3) after obtaining the King's Ring.
- In a chest past the two Elite Giants in the Black Gulch.
- Drops from the Imperfects lurking in Dragon's Sanctum, near the Lair of the Imperfect bonfire.
- In a metal chest in Brume Tower after the Foyer bonfire, behind a breakable wall. The wall can be destroyed by chasing a Cask Runner toward it and hitting it with fire. A total of 8 Petrified Dragon Bones are in the chest.
This video shows how to quickly get as much Twinkling Titanite and Petrified Dragon Bone as desired. The use of Yearn facilitates the process, though the Crown of the Sunken King DLC needs to be installed. This method does not work in Scholar of the First Sin since using a Bonfire Ascetic does not reset chest loot.