Blasphemous

Fervor is this games version of "mana" and is needed to use your prayers and ranged attack. It is represent by the blue bar in the top left corner. To max out your fervor bar you have to find all 6 Oil of the Pilgrims.

• Desecrated Cistern. This is close to the exit to Albero, in a vertical shaft. About halfway through the shaft, attack the left wall to reveal a secret area.
• Graveyard of the Peaks. Two screens before entering the Convent of Our Lady of the Charred Visage, you will climb a vertical room. About halfway up, attack the right wall to reveal a secret area with the Oil.
• Grievance Ascends. Requires Blood Perpetuated in Sand relic. At the bottom of the 3rd vertical shaft of the area you can find a Blood Fountain to refill your Bile Vessels. If you have the Blood Perpetuated in Sand relic equipped, you can jump along some platforms to reach this Oil of Pilgrims.
• Mother of Mothers. At the bottom of the area attack the left wall to reveal a secret area. This is just before the entrance to Library of Negated Words.
• Library of the Negated Words. At the end of the area attack the left wall to reveal a secret area. This is just before the entrance to The Sleeping Canvases.
• Wall of Holy Prohibitions. In the bottom left corner of the area, in the same room as the Sphere of the Sacred Smoke Rosary Bead, attack the left wall to yet again reveal a secret area with this Oil.

If you would watch a video on where to find them, please refer to the one linked below: