In official Russian Orthodox Church "Life of St. Stephen of Perm" he succeeded without killing anyone. Actually Russian Orthodox Church canonical law prohibits a priest who killed any human continue priestly ministry - that is why modern Russian priests are so afraid to drive cars and often hire drivers.
In Komi-Zyrian folklore St. Stephen of Perm is depicted as the most powerful shaman or pagan deity. According to pagan tradition shaman who had lost the competition must die. In folklore St. Stephen of Perm was all-time winner, shamans-losers were killed by Komi folk, by St. Stephen companions or by St. Stephen himself (St. Stephen kills shamans by smashing their heads with cross).
I think that historical truth is somewhere between sweet official Church story and cruel folk stories. I am sure St. Stephen of Perm, the great missionary, was neither "pagan deity" nor "killer of shamans" of Komi-Zyrian legends. And yet some conflicts between Pagans and Christains could take place during Christianization of Komi-Zyrian lands.
Picture attached - St. Stephen of Perm and Komi-Zyrian Christains rejoicing in Paradise:
[Ed. Note] From Bible verses such as Revelation 21:4, we know that there is no death in heaven; thus, any of these stories and photos of heaven that depict death (as the fish in the boat above), cannot be inspired by God.