ST. MICHAEL THE ARCHANGEL
Glorious Prince of the heavenly hosts and victor over rebellious spirits, be mindful of me who am so weak and sinful and yet so prone to pride and ambition. Lend me, I pray, thy powerful aid in every temptation and difficulty, and above all do not forsake me in my last struggle with the powers of evil. Amen. [http://www.catholic.org/prayers/prayer.php?p=778]
Worthy of repetition. To Jesus through Mary. Just as she interceded to her Son at Cana. Jesus, being God as well as man, knew there was no wine: yet He allowed His mother to intercede and to be the one to say to the servants in turn, "do as He tells you." This is Jesus and His mother.
Saul went to a witch to conjure the spirit of Samuel. She was terrified when she realized she had contacted a holy man, and Samuel chastised Saul for doing this. That was necromancy.