The neutron star ( NS ) low-mass X-ray binary ( LMXB ) the Rapid Burster ( RB ; MXB 1730-335 ) uniquely shows both Type-I and Type-II X-ray bursts . The origin of the latter is ill-understood but has been linked to magnetospheric gating of the accretion flow . We present a spectral analysis of simultaneous Swift , NuSTAR and XMM-Newton observations of the RB during its 2015 outburst . Although a broad Fe-K line has been observed before , the high quality of our observations allows us to model this line using relativistic reflection models for the first time . We find that the disk is strongly truncated at 41.8 ^ { +6.7 } _ { -5.3 } gravitational radii ( \sim 87 km ) , which supports magnetospheric Type-II burst models and strongly disfavors models involving instabilities at the innermost stable circular orbit . Assuming that the RB magnetic field indeed truncates the disk , we find B = ( 6.2 \pm 1.5 ) \times 10 ^ { 8 } G , larger than typically inferred for NS LMXBs . In addition , we find a low inclination ( i = 29 \pm 2 ^ { o } ) . Finally , we comment on the origin of the Comptonized and thermal components in the RB spectrum .