Tauroctony relief from Oescus
TNMM 2481 ↔ CIMRM 2247
Relief in tuff (H. 0.615 Br. 0.72 D. 0.27–0.30), found at Ghighen. In two fragments. Sofia, National Museum.
The relief is surrounded by a projecting border. Mithras as a bullkiller, both the god and the r. torchbearer are represented laughing. The two torchbearers are standing cross-legged and hold the torches upwards. The dog, possibly the scorpion, but no traces of other animals. The bust of Sol in a crown of six rays and the bust of Luna in a crescent in the upper corners. In the centre of the four sides of the projecting border is a cross; before the head of Mithras is a swastika.
References
Dobrusky in Sbornik XVI, 1900, 44 No. 10 and fig. 21; Kalinka, Denkm., 136 No. 148 and fig. 41; Kazarow in BSAB 1911, 54f No. 5 and fig. 5; Dölger in Antike und Christentum IV, 1934, 62ff and Pl. 1; LeRoy Campbell in Berytus XI, 1954, 46 No. 80. See fig. 623.
- Vermaseren, Maarten Jozef (1956) Corpus Inscriptionum et Monumentorum Religionis Mithriacae

Comments
Based on the CIMRM, this museum should have the mother-load of mithraic pieces for Bulgaria, but this is the only one (seemingly) on display. I’ve written to them for more info... fingers crossed. 😉