Fire Magic is the magic of flames, heat and cold, and of darkness and light, but is also the magic of emotion, passion, inspiration and creativity. While Air is the magic of design, Fire is the magic of creation . . . Fire magic can inspire deep emotion. Ether is the element of mystery, time, and magic itself. This includes astral travel, divination, demon summoning, teleporation, and the creation of pocket realities.
Spells involving raw magical force, or the manipulation of other spells are also Ethereal.
If he is missing an Element, the spell is beyond his power and he must try a different approach. If the mage has all of the Elements required, he rolls against the lowest applicable Element, or his Thaumatology skill, whichever is lower. When the player describes his spell, he should be careful to describe the means as well as the end. Of course, it's usually wise to have at least a half-point into all five elements, to cover all the bases. There is, however, some minor benefit to ignoring elements.