Henstridge, M. Fisher, A.S. Hoffmann, M.C. Huang, Z. JACoW Publishing Geneva, Switzerland Ultrafast THz pulses with energies of several µJ drive exotic non-equilibrium phenomena in complex materials, yet many of the underlying microscopic mechanisms remain unknown. Current strong-field THz sources rely mostly on difference-frequency mixing of near-infrared laser pulses in crystals at few-kHz repetition rates, but the extension of such sources to higher repetition rates suffers from reduced pulse energies and crystal damage. Here, we present a wiggler-based THz scheme capable of delivering 3-30 THz pulses with energies of 100 µJ at the 100 kHz rate supported by LCLS-II. Two time-delayed electron bunches independently drive the wiggler and x-ray undulator to generate precisely synchronized and optimized x-ray and THz pulses for pump-probe experiments. We built a model transport line to address the significant challenge of transporting the THz emission over the minimum 150-m distance necessary to reach the experimental halls. This concept, scaled to 12-m, has been tested with the 28 THz output of a CO₂ laser. Results indicate that the THz emission can be transported over 150-m with an efficiency near 90%. Further testing is underway at 3.5 THz with a quantum-cascade laser.