This tale is simple and direct. It is a hero short story set in abbreviated fashion. I would like to see it expanded to include details: the chant being made (included as dialogue), the struggle of the demon (there must be a risk to the wizard presented, a potential for harm or death), the final defeat set out in detail. All in all it is a brief but tasty sample of a great epic. I would remove the extra punctuation as well. Too generous use of commas detracts from the spell of the narrative.