Context about 40k and the Netflix Castlevania animation:
Barabas Dantioch was an Iron Warriors Space Marine who stayed loyal to the Imperium during the Horus Heresy. During the Heresy, Dantioch activated and blew up an ancient beacon called Pharos to stop the Night Lords from finding their Primarch. However, the destruction of Pharos caught the attention of the Tyranids, suggesting Dantioch unknowingly brought a future threat to the Imperium.

The comic is reference from one scene of Season 1 of Netflix's Castlevania where the Bishop who was responsible for the death of Dracula's human wife and Alucard's mother, gets confronted by demons in his church, where they mock the bishop, who still delusional believes his actions including harming the good guys was allowed by God, by pointing out because he have become corrupt and killed an innocent woman, God abandoned him to be punished and the demons "thank" him since his evil cause an vengeful Dracula to summon the demons to attack Transylvania.