Unicorn horns were not the only ones, there were also the iron arrows that also could be used with a normal longbow on f2p back then, but they fixed that bug later on though
I've gotten 4 so far, and im getting more annoyed with them every time i get them. only the first time it is fun, and the mask is just ugly, but hey thats my opinion, i should also fail next time to get frogland music