Program: GS-2025A-DD-105

EP250304a, a rare X-ray flash (XRF) transient, challenges prevailing models of gamma-ray burst/supernova (GRB-SN) connections and unlocks the diversity of jet-driven stellar explosions. Alongside counterparts like XRF 060218, XRF 100316D, and EP240414a, etc., EP250304a exhibits unique properties that violates standard GRB/XRF paradigms. Currently at peak brightness (20.5–21.0 mag in r-band), EP250304a is an ideal target for Gemini Multi-Object Spectrograph (GMOS) spectroscopy. We request three-epoch optical spectra urgently with GMOS-S needed to: (1) track evolving spectral features (e.g., Fe II, Si II), (2) resolve the origin of its soft X-ray emission and spectral evolution, (3) confirm the physical link between the XRF and SN, and (4) uncover the nature of the SN host. These observations will test whether EP250304a represents a low-luminosity GRB with a choked jet, a stripped-envelope SN with weak relativistic ejecta, or a new subclass of engine-driven transients.