In the last years, the numerous improvements made in material research (such as on topological insulators and antiferromagnetic materials), interface quality and device engineering have been central to both explore spin-based physics at THz frequencies and investigate to new concepts of spin based THz devices. These cover the full THz block chain (broad and narrowband THz generation and detection, together with control of radiation properties such as polarization and ellipticity) as well as new approaches for THz imaging and encoding THz information. The widespread interest and progress in spin-based THz physics and devices continues to accelerate requiring joint efforts from magnetism, optics and engineering research communities. This workshop will bring together world-leading scientists from these broad range of communities, generating further collaborations and developmentsin this emerging field.