Based on your theme of Vampires, Werewolves, Demons, and Merfolk, I will create a color palette that embodies the mystical, dark, and vibrant aspects of these creatures.

 <Dark Mystic Creatures> 
1. Blood Red - 
          
          #9B1B30
        - A deep, rich red symbolizing the essence of Vampires and their connection to blood. 
2. Midnight Black - 
          
          #1C1C1C
        - A dark black representing the night, ideal for Werewolves and the mystery surrounding them. 
3. Infernal Orange - 
          
          #FF5E00
        - A fiery orange that captures the chaotic energy and intensity of Demons. 
4. Ocean Deep Blue - 
          
          #003D5B
        - A dark, tranquil blue reflecting the depths of the ocean, perfect for the Merfolk. 
5. Silver Moonlight - 
          
          #B0C4DE
        - A soft, silvery hue representing the moonlight that guides Werewolves and adds elegance to the palette. 
6. Bloodstone Green - 
          
          #4A7C1A
        - A dark green reminiscent of ancient forests, ideal for nature-loving Werewolves and the mystical aspects of the Merfolk. 
7. Ethereal Purple - 
          
          #5D4C85
        - A mystical purple that conveys otherworldly themes, suitable for all supernatural beings. 

This color palette combines elements of darkness, mysticism, and nature, making it suitable for your roleplay server while allowing each creature to have its unique color association.

What specific features or themes would you like to incorporate in your server? Would you like to focus more on one creature than the others, or do you want to balance them equally?