Jet substructure techniques have emerged as an essential tool for new physics searches at the LHC. In this talk, I highlight the ways that theoretical studies of jet substructure have revealed fascinating new phenomena in QCD. Using the Run 1 ATLAS diboson excess as motivation, I present jet substructure observables that blur the boundary between perturbative and nonperturbative aspects of QCD, yielding new insights into the universality of the collinear limit.
