Squall quickly turned to the student with questions, "Yes, Overload magic is much more complex than magical threshold, though magical threshold is the core of it. There is also threshold elasticity, threshold growth, and magical stability, the properties of the material in use, and we have not even started to talk about systems in overload magic, which are two or more objects made of different materials which freely shared magic energies between all parts, and equal systems and unequal systems. As for your other question, it is a process of knowing the magical threshold of an object, as well as related variables, and knowing how much magic you have left. Overload magic may seem simple at first, but requires a good eye for magic, a good control over your magic, and a a good tank of magic. You also must have cost-benefit analyze skills to know when overload magic would be better or another form of magic would be better, but all types of spellcasters can benefit from that skill." He said, very clearly but also very quickly. 

He then decided that he should do something about the fight outside. A grin came across his face. He reached into his pocket, and teleported what he grabbed from there down near where they was fighting. From a distance, it was really hard to make out. But those that could, it was a silver necklace with a decoration at the end which looked like a tree growing into a book.