The mixed elemental attacks that are sent towards the Arch Lich by Emrys is not normal to say the least. Usually if two or more elements are mixed with each other, a catastrophic effect will happen. Usually when two elements are mixed together, an explosion would usually result if the two elements are not perfectly mixed.
The spell that Emrys used just goes to show that he has understood the nature of each element. He knew how to perfectly balance the needed amount of a certain element to synergize them perfectly. Contrary to what other sorcerers use, Emrys does not use the same amount per each element.
The popular notion for magic users using two elements is to use the same amount of power but that is not really the case for the game Pandemonium. In Pandemonium, an elemental system called Elemental Harmony is implemented and magic is not really what others believe that it is simply imagining it.