The Ghoul Mask is an accessory in the game Blox Fruits that can be bought from El Perro, who is located in the Cursed Ship in the Second Sea. It costs 50 Ectoplasm. The Ghoul Mask provides the following buffs:

• Increases Energy by 500
• Increases Movement Speed by 35%
• Grants Life Leech ability

To summarize, the Ghoul Mask in Blox Fruits is an accessory that can be purchased from El Perro in the Cursed Ship in the Second Sea for 50 Ectoplasm. It provides buffs such as increased Energy and Movement Speed, as well as the Life Leech ability.