  For decades, AE Aquarii (AE Aqr) has been the only cataclysmic variable star
known to contain a magnetic propeller: a persistent outflow whose expulsion
from the binary is powered by the spin-down of the rapidly rotating, magnetized
white dwarf. In 2020, LAMOST-J024048.51+195226.9 (J0240) was identified as a
candidate eclipsing AE Aqr object, and we present three epochs of time-series
spectroscopy that strongly support this hypothesis. We show that during the
photometric flares noted by Thorstensen (arXiv:2007.09285), the
half-width-at-zero-intensity of the Balmer and HeI lines routinely reaches a
maximum of ~3000 km/s, well in excess of what is observed in normal cataclysmic
variables. This is, however, consistent with the high-velocity emission seen in
flares from AE Aqr. Additionally, we confirm beyond doubt that J0240 is a
deeply eclipsing system. The flaring continuum, HeI and much of the Balmer
emission likely originate close to the WD because they disappear during the
eclipse that is centered on inferior conjunction of the secondary star. The
fraction of the Balmer emission remaining visible during eclipse has a steep
decrement and it is likely produced in the extended outflow. Most enticingly of
all, this outflow produces a narrow P-Cyg absorption component for nearly half
of the orbit, and we demonstrate that this scenario closely matches the outflow
kinematics predicted by Wynn, King, & Horne. While an important piece of
evidence for the magnetic-propeller hypothesis---a rapid WD spin
period---remains elusive, our spectra provide compelling support for the
existence of a propeller-driven outflow viewed nearly edge-on, enabling a new
means of rigorously testing theories of the propeller phenomenon.
