NOTE DIFFERENT ROOM
In this talk, I will explore the factorisation and universal building blocks of gauge-theoretic scattering amplitudes at high energy. After a brief review of classical concepts in Regge theory, I will introduce the shockwave (or Balitsky/JIMWLK) formalism, which provides an effective description of the high-energy dynamics via correlators of infinite Wilson lines. I will continue by showing how this framework can be pushed to second order in the logarithmic expansion (NNLL), where it provides a simple explanation of Regge factorisation breaking. Finally, I will discuss the extraction of the two-loop Lipatov vertex and the three-loop gluon Regge trajectory in QCD and N=4 super Yang-Mills making use of recently computed scattering amplitudes.