Make candy clay in advance. Prepare candy clay recipe following recipe directions, using lavender Candy Melts candy.
Shape candy clay horns. Make cone-shaped horns, 1 in. x 3/8 in. dia. Shape into a curve. Set aside.
Bake doughnuts. Prepare batter following recipe directions. Bake and cool doughnuts following recipe directions.
Cover top with candy. Place doughnuts on cooling grid over parchment-covered board. Melt green and lavender Candy Melts candy, separately, according to package directions. Use melted candy in cut decorating bag to cover top of doughnuts and dripping down sides. Tap to smooth and remove excess candy. Chill until firm, about 10 to 15 minutes.
Decorate lavender monster. For lavender monster, melt orange Candy Melts candy according to package directions. Use melted orange candy in cut decorating bag to pipe dots. Chill until firm, about 3 to 5 minutes.
Attach details. Use scissors to trim yellow section off candy corn. Use melted green or lavender candy in cut decorating bag to attach candy corn teeth and candy eyeballs. Attach horns to green monster. Chill until firm, about 3 to 5 minutes.