Understanding and controlling runaway electrons (REs) remains a critical challenge for future tokamak reactors. While REs are initially accelerated by strong electric fields, their maximum energy and confinement are strongly influenced by pitch-angle dynamics, which govern synchrotron damping and loss mechanisms. Wave–particle interactions have been shown to resonantly enhance pitch-angle scattering, thereby limiting RE energy. The natural resonance between REs and the toroidal field ripple (TFR) has been hypothesized to produce a similar effect, which may explain the experimentally observed maximum runaway energies on the Tokamak à Configuration Variable (TCV). A hardware upgrade on TCV will enable controlled modification of the TFR by reducing the current in every other toroidal field coil, producing a new n=8 ripple. The system is designed to divert up to 20% of the coil current through a resistive circuit added in parallel, which corresponds to an expected 10% increase in ripple amplitude. This approach enables systematic, discharge-to-discharge scans of the applied n=8 ripple, providing a controlled means of probing its impact on RE dynamics. The resistive circuit will be activated during the discharge to maximize the stationary phase of the imposed perturbation, ensuring reproducible conditions for comparison across discharges. At significant ripple amplitude, this resonance is expected to impose a new maximum RE energy. While the intrinsic n=16 ripple interacts near p_{||} \approx 42 m_e c, the applied n=8 perturbation is expected to drive higher-order harmonic resonances, including a second harmonic near p_{||} \approx 47 m_e c across much of the plasma cross-section and a third harmonic near p_{||} \approx 28 m_e c at the edge. The observation of these new energy limits using the MANTIS system will serve as a strong validation of modeling efforts. The final design and hardware procurement are currently underway, with experiments planned in late 2026 and early 2027. This positions TCV to deliver the first controlled experimental study of these ripple resonances and the effect of pitch-angle scattering on RE dynamics.