Along with the Muadhitain and Ayatul Kursi and other prescribed Verses and Duas the recitation of Allah's Names Ya Mu'minu and Ya Maniu is effective against magic, jinn and witchcraft. The writing of the Names Allah, Al Mu'min and Al Mani and placing them around Your neck is very effective also. Those suffering from waswas in Salaat can place the Taweez (Allah's Names mentioned above) in their Head covering on their Heads and this has been very effective against doubts related to the Prayer. The proof of this is by analogy that placing something of blessing near the Head against the enemy was the practice of Hazrat Khalid Bin Walid who would place the Hair of the Messenger of Allah (SalAllahu Alaihi wa Sallim) in his helmet during battle. The Names of Allah carry Immense Blessing such that writing Them, reciting Them and asking Allah for needs Through Them is a proven medicine.