I made the horn from black gum paste, and then curled some wire to fit around the horn.
I twisted short, thinner pieces of wire around the curled wire and glued them in place. These short pieces are supposed to be the barbed part of the barbed wire.
Then I used a bench scraper to smear all the colors together. For the first swipe I went clock-wise.
Then to keep it from looking like an ombre cake I used the bench scraper again, but the second time I went in a counter clock-wise direction to break up the uniform streaks. (Got this tip from Cupcake Gemma.)
Next the cake was adorned with its black horn, bitten ear, and a mane of yellow, green and purple rosettes. I tinged the colors with a bit of black to give them a decaying look.
My niece, who dressed like a unicorn for Halloween, loved her Zombie Unicorn Cake.
Happy Halloween from Lucille the Zombie Unicorn