<Shades of A4C8E1 with Shadows>
1. Light Blue - 
                            
                            #B7D1E8
                         - A soft, airy shade that complements A4C8E1, perfect for creating a light and breezy feel.
2. Slate Blue - 
                            
                            #A4C8E1
                         - The base color, a serene and calming blue with a hint of gray, ideal for a soothing palette.
3. Deep Sky Blue - 
                            
                            #8DB8E8
                         - A brighter, more vibrant blue that adds energy and liveliness to the palette.
4. Steel Blue - 
                            
                            #4682B4
                         - A medium-dark blue with gray undertones, offering a robust and sophisticated touch.
5. Rim Light - 
                            
                            #E1F0FF
                         - A very light, almost white shade with a hint of blue, perfect for highlights and rim lighting effects to add depth and dimension.
6. Shadow Blue - 
                            
                            #6A9DC2
                         - A darker shade that adds depth, creating a subtle shadow effect while still harmonizing with the palette.
7. Dark Slate Blue - 
                            
                            #4A7A91
                         - A rich, muted blue that can be used to create more pronounced shadows, enhancing the three-dimensionality of illustrations.

This updated color palette includes shadows to provide depth and contrast, enhancing the overall visual appeal of your design. The shadows can help create a more dynamic look in your cartoon illustration.

What specific areas of your illustration are you looking to apply these shadows? Would you like any additional colors or effects to enhance your project?