Necromancy is the black art of trying to call up the dead for help and information.  Different methods have been used in this attempt.  Sometimes it is elaborate rituals with robes and incense and altars.  Quite often the necromancer slept in a burial ground looking for a message. Or they might surround themselves with weapons of death and skulls.

One interesting method involved making food and drink from corpses.  The idea is that the person somehow becomes part of you and that alone can mean you are being led to do the best thing to solve a problem.  The problem could even be something spiritual like a gambling addiction. 

A variant of this was using dead materials as food such as black bread and even wine which are evidently substitutes for eating the body and making soup.    They were consumed as signs of the body and blood of the dead person so that you might attract something about them and get forbidden information or guidance from them. 

The preference was if a person died then you engaged in the rituals as soon as possible for it was believed their powers to help you would fade over time.  The voice of long dead ghosts was said to be barely audible.  You needed to talk to them as soon as their bodies were cold.

A person dying a tragic bloody death invited necromancers who used gruesome sick imagery and rites to connect with them, to establish rapport. 

When you know this you see the Catholic doctrine, that Jesus is there body and blood in the bread and wine of Mass and his sacrifice is also made present, in a new and terrible light.

Jesus supposedly started the Eucharist during a Passover Meal. Passover as you can see from Exodus 12 is a gruesome vindictive event.  An animal is killed and is related to another feast where those who eat yeast are threatened with excommunication.  The blood is put on the doorpost so that an angel will kill people who don't mark their abodes with blood.  It reeks of black magic.  It reeks of evil angels.  As for Jesus' Passover meal, "No foreigner may eat it.  Any slave you have bought may eat it after you have circumcised him." Exodus 12:43,44.  So the slave's body is your property.  How Jesus could see this as a celebration, and he called it that, says loads about him.

Worse Jesus would have known that the priesthood made a tidy little earner from its rituals and killing animals which they feasted on in the name of communion (Leviticus 23, Nehemiah 10).  And why does God spend chapter after chapter detailing the hideous rites he wants as if people were not suffering and as if the rites were what mattered?

The Church says that Jesus risen and glorious is present in the Mass under the appearance of bread and wine when the priest reenacts the last supper where Jesus said bread was his body and wine was his blood.  But at that point the priest uses Jesus' words saying the bread is his body which will be given up for you or is being given for you.  The same with the wine called his blood - bread and wine are blessed separately as Jesus' flesh and blood were separated when he bled on the cross.  Jesus is clear that if the bread and wine are turned into anything it is his LIFELESS BODY AND DEAD BLOOD.  Jesus when he said the bread was his body and the wine is blood did not say he meant living items by them. Clearly he did not. They stand for a dead body and the blood it has shed. In the light of Deuteronomy 14:21, a Jew was regarded as sacred and was banned from eating anything dead but was permitted it give it to a foreigner for “you are a people sacred to your God.”  Symbolic eating of a carcass and drinking blood would offend this rule too.  Its about the sentiment not just what is consumed. 

Incidentally, if the last supper is a myth that a real Jesus would not have countenanced then the whole Christian system is nonsense.

 If the consecration of the Mass says it is the dead murdered body of Jesus then Catholic doctrine that it is the living risen Jesus is covering that up. And it does say that.  Liturgical actions speak louder than Church decrees about doctrine or even catechisms.  It would not be the first case where a religion's public doctrine is not its real doctrine.  It follows the Church does not really intend to make the living Jesus present. It is obvious why trying to turn bread and wine into the dead body of Jesus and his dead blood is necromantic and occult. It is sorcery.  A dead Jesus cannot feed your soul and its disrespectful to him to try to make him present.  It is grave-robbing.  It is bringing about the dead Jesus or there is no change at all intended if this cannot be done and the Church knows it. It says it cannot be done. So there is a problem with intention: the Church does not intend to give us Jesus but bread that it pretends is Jesus or it intends to give us a dead impotent Jesus.  It is like Jesus' corpse is used against him as a living saviour who lives in us.

Calling up the undead as in vampire matches what the Catholic Church is doing in the Mass.  When occultists used to try to trap demons and dead people in the light of a candle so that they could get signs and omens they were unaware that the parish priest was doing something similar!

The Church says that to take communion without seeing that it is Jesus or taking it while having declared yourself independent of God by serious sin or opposition to God is you eating and drinking judgement to yourself.  The New Testament warns that doing this causes grave illness and even death.  The sacrament has vindictive overtones.

All of these things point to the Mass as an occult enterprise.