"Blood magic" is different from redemptive suffering. The suffering of the person or animal being sacrificed isn't your own suffering. This is why Nietzsche admired ancient Judaism: he liked the idea of a proud, conquering people, impervious to taking pity on others, seizing the land by violence and calling it their own as a gift from their god. I have little doubt he would equally admire modern Israel (or, Israel: The Reboot). Palestinians? Lebanese? F*ck them; they don't matter because they're not you. Might makes right, law of the jungle, king of the heap. You're special. You're chosen.
In The Antichrist, Nietzsche admitted that the Christian view of suffering comes from Judaism—but it came from what he considered a degenerate form. In Judaism it used to be that if you were prospering, it meant God liked you. If you were suffering, God was displeased with you. This is why Job and his friends were so confused about Job's plight. They couldn't possibly know that it was God acting on a friendly wager with the devil. You could even have a shitty life full of suffering simply because God was angry at your parents or grandparents (Exodus 20:5). It was only later, when the Jewish kingdom fell, that the Jews, now the trod-upon victims of military supremacy, first under the Seleucid and then the Roman boot, revised their attitude according to their misfortune.
From this came the Messianic fervor and a collective delight in revenge fantasies. Their sufferings were now righteous: the birth pangs of a glorious new age, when Jewish supremacy would reign over the Gentiles. Suffering becomes redemptive; it manifests the works of God. John chapter 9 expresses it completely, where Jesus overturns the traditional view. Because both Jesus and Paul were caught up in this stuff (which Nietzsche considered a decadent, late Judaism) he referred to them as "superlative little Jews." Which is pretty rich, because what is Romans 5:3-4 but a formulation of "what doesn't kill you makes you stronger?" It's a very Christian aphorism. Schopenhauer held the sentiment of a refined pagan: that it is ignoble and unseemly to suffer overmuch. Good taste rebukes the sufferings of the world; you should quit while you're ahead, and certainly have the decency to not bring any innocents into this seething whirl. You know the Larkin poem.