For a frog monster in a Gravity Falls art style, we can create a pattern that complements the existing color palette and adds visual interest to the character’s body. Here’s a suggested pattern description along with a color reference:

Body Pattern Description:

• Pattern Type: Spotty Texture
• Pattern Colors:
  • Darker spots for contrast against the vibrant swamp green base, using colors such as Mud Brown and Night Sky Purple.
  • Lighter speckles to add depth, which can be created using shades of Lily Pad or a very light version of Swamp Green.

Here’s a suggested addition to the color palette that can represent the pattern colors:

 <Frog Monster Body Pattern>
1. Swamp Green - 
          
          #319179
        - A vibrant green reminiscent of the swampy habitats where frogs thrive.
2. Swamp Green Shade - 
          
          #1E5B4D
        - A darker shade of swamp green for shading.
3. Mud Brown Spots - 
          
          #4B3D27
        - Deep brown spots that create a contrast against the green skin.
4. Night Sky Purple Spots - 
          
          #4A2C6D
        - Dark purple accents that add a unique, mysterious touch.
5. Light Lily Pad - 
          
          #C1E5D0
        - A very light version of lily pad green for subtle highlights or speckles.
6. Eye Green - 
          
          #A2D600
        - A vivid and luminous green for the eyes.
7. Tongue Pink - 
          
          #D85E8B
        - A playful pink for the tongue.

Pattern Application:

• The Mud Brown Spots and Night Sky Purple Spots can be randomly distributed across the body, giving the frog monster a lively and textured appearance.
• Light Lily Pad can be used for small highlights or speckles throughout the body, enhancing the depth and dimension.

Would you like to delve deeper into any specific details of the pattern, such as size, placement, or additional textures? Or perhaps work on another aspect of the frog monster character?