$CP$ violation in multi-body charmless $b$-hadron decays at LHCb

Long-distance resonant dynamics along with a sizeable weak phase present in multi-body charmless $b$-hadron decays leads to rich structures of $C\!P$ violation as a function of the phase space. Amplitude analysis provides a deeper understanding of the mechanisms that generate strong phase variations, which are responsible for this effect. We present the amplitude analyses of $B^+ \to \pi^+ K^+ K^-$ and $B^0_s \to K^0_S K^\pm \pi^\mp$ decays. For the former, $C\!P$ asymmetries of the contributing quasi-two-body resonances are measured.Charmless $b$-baryon decays represent a promising opportunity to make a first observation of $C\!P$ violation in the baryonic sector. We also present the most recent measurements of four-body charmless $b$-baryon decays performed by LHCb.