Assemble witch hats. Transfer cones and cookies to parchment paper. Tint 1 cup icing orange. Tint 1 cup icing purple following color combinations provided.
Prepare two decorating bags with tip 2B. Fill separately with orange and purple icing. Using orange icing, with smooth side of tip facing out, pipe band around wide end of half the cones. Repeat with purple icing on the other half. Let set, about 15 to 20 minutes.
Pipe small amount of orange or purple icing in middle of cookie; place cone on top of cookie.
Tint ¼ cup icing yellow following color combinations provided. Prepare second decorating bag with tip 3 and yellow icing. Pipe buckle around band.
*Combine Violet and Rose icing colors for purple color shown. Combine Golden Yellow and Lemon Yellow icing colors for yellow color shown.