This story develops the “Baron Blood as street vigilante” plot that’s been bubbling under for a while.
Strange tries to exorcise the vampirism out of his brother, but instead unleashes Mephista.
Mephista and Satannish trick Strange into bringing them to Mephisto’s realm—his daughter Mephista has abandonment issues. There’s some fighting, dad and daughter reunite, and then there’s a cliffhanger telling us that the next issue will tie into the Infinity Gauntlet event.
My problem with these kinds of stories is that we’ve seen it all before, but as far as Mephisto stories go this one isn’t terrible.