Mary had two very human parents, she acknowledges to the angel that she is the handmaid of the LORD, a servant, of lowly estate.
After her greeting and exchange with Elizabeth, Mary says:
"My soul magnifies the Lord, and my spirit rejoices in God my Savior, for He has regarded the low estate of His handmaiden. For behold, henceforth all generations will call me blessed; for He who Is mighty has done great things for me, and Holy Is His Name. and His Mercy is on those who fear Him from generation to generation..."
It is clear in Scripture that Mary knows God and she clearly knows it is not her. Mary even acknowledges she was in need of being saved. She was saved like all of humanity by the Passion of her own Divine Son. Catholics believe that Mary was saved "in advance" or at conception, that through a unique Gift, God applied the Merits of Christ's Passion and Resurrection to Mary at her conception, preserving her from any and all sin, that is the basic definition of the Immaculate Conception. Not through any merit of her own, but that Almighty God wanted the Sinless Lamb to be born of a sinless Mother, this is the inverse of "nothing impure shall enter heaven. " Since God will not allow anything impure to enter heaven, why would He allow anything impure to enter His Eternal Son.
It is God WHO created Mary to be a worthy bearer of His only Begotten Son.
Necromancy is a special mode of divination by the evocation of the dead, which is the seeking after knowledge of future or hidden things by inadequate means. Catholics never do that.
You're right. I was taking a broader meaning for the word, communicating with those who have died. I probably should've been more precise.