At the outset, let me address the likelihood that this post will eventually be visited by someone who has unspeakable plans for a unicorn, is holding a unicorn hostage, or who intends to affix a unicorn to ducting for less nefarious reasons. First, it's duct tape with a unicorn design (Amazon). As in pictures of unicorns are printed on the tape. Second, duct tape is in fact no good for use with ducting. Third, no special tape is required to immobilize or silence unicorns: any good store brand will do.
Unicorn Duct Tape [Amazon]