We present time-resolved photometry and spectroscopy of the recently classified polar MASTER OT J132104.04+560957.8 .
The spectrum shows a smooth , non-thermal continuum at the time of maximum light , without any individually discernible cyclotron harmonics .
Using homogeneous cyclotron modeling , we interpret this as cyclotron radiation whose individual harmonics have blended together , and on this basis , we loosely constrain the magnetic field strength to be less than \sim 30 MG .
In addition , for about one-tenth of the orbital period , the Balmer and He I emission lines transition into absorption features , with He II developing an absorption core .
We use our observations of this phenomenon to test theoretical models of the accretion curtain and conclude that the H and He I lines are produced throughout the curtain , in contravention of theoretical predictions of separate H and He I line-forming regions .
Moreover , a significant amount of He II emission originates within the accretion curtain , implying that the curtain is significantly hotter than expected from theory .
Finally , we comment on the object ’ s long-term photometry , including evidence that it recently transitioned into a prolonged , exceptionally stable high state following a potentially decades-long low state .