Prayers to the saints are not idolatry nor necromancy. “And as touching the dead, that they rise: have ye not read in the book of Moses, how in the bush God spake unto him, saying, I am the God of Abraham, and the God of Isaac, and the God of Jacob? He is not the God of the dead, but of the living.” -Mark 12:26-27 The martyrs whose blood cry from before the throne of God are, if anything, more alive than us, therefore, if you request of the early Christian martyr Lucy of Syracuse, that she pray to God, this is no different than asking another Christian to pray for your child’s eyes.
Read Jesus’ parable about the rich man Lazarus. Luke 16:19. There is an impenetrable gulf or divide that separates even communications between the living and the “dead”, or else Lazarus could have sent a warning to his brothers. The saints who are asleep in Christ cannot hear us or intercede for us,