You are the apprentice of the esteemed wizard Merlin. It's the day of your final magical exam, but alas, you have not studied the course material! Thankfully, Merlin’s book of spells can be deciphered using intelligence and wit, as Merlin has included some ancient runes in the book to help in the spell casting process. As with the casting of any spell, act with care. If you perform the spell correctly, you'll know the sole criterion that Merlin is judging you upon today!
Note: Please ignore the blue underlines, those are Microsoft Word's autocorrect nonsense and are unrelated to this puzzle. In addition, you should refer to the text as quoted at the bottom of this post instead of the picture due to a slight error.
Text from the picture: