Sounds a lot like Altered Carbon, or the Takeshi Kovacs novel series on which Altered Carbon was based.
Like Jason Aaron's Doctor Strange run where an army of mage-killers from another world tried to kill all magic in this one using some secret super-science?
Hmm, Black Widow's even foreshadowed the X-Men's, in a manner of speaking, since like with the X-Men on Krakoa, the Black Widow operatives' memories and personalities were kept in psychic storage to be downloaded into new clone bodies whenever they were killed.
A digital copy of his brain, uploaded into a cloned body from DNA taken from his corpse by the Jackal (Ben Reilly, who was put through a similar process to come back from the dead).