Deuteronomy 18:11 - Or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer.
For me that is clear enough.
Sorry, but no cigar. The communion of saints was an article of faith from the very earliest decades. When you die you do not leave the Church. If the Evangelist John could be granted a glimpse of the saints in heaven gathered around the Throne worshipping the Lamb, it’s a pretty safe bet they are there. If they are in Christ (do you deny that) and if you are in Christ, then they and you are in Christ. To ask them, in and through the mystery being in Christ (which is what we are in) to pray with you is not divining or sorcery and the claim that it is doesn’t past the elementary reasoning test.