Will
Any that know the Sunvaar, the rare breed of Dragon, know they are a species of intense emotion. When they feel rage, it is absolute. If they touch upon happiness, it could make an audience weep. Sadness strains the mind of those around them with it's unimaginable level of utter anguish.
Thus is the same of the Will. Drakonic Magic at its finest and rawest form is Will. It needn't a word to activate, nor a written symbol. Just will it. Do it.
Despite the way that sounds, being used can force a variety of things. It could work perfect, with exact effects wanted being displayed. Or emotion can cloud the will, and the intention goes awry. If a Sunvaar Wills a tree to grow in moments from a seed, and feels happy, the tree could sprout and be the most healthy, durable, noteable of it's species in history. If the Sunvaar is angry however, maybe the tree sprouts with more live characteristics, and starts attacking anythat come near, or maybe instead the seed becomes a acidic thing that melts the ground around of it killing life for miles.
A Rider can use Will Magic. However, it is even more risky. Think about yourself, as an individual. What is something you want right this moment that magic can help achieve? Now think of the emotion present while this has crossed your mind. If you only think a single emotion was present, there is always a chance you were wrong. Maybe it was a dozen, and each altering the outcome.
Sunvaar are absolute beings, that feel absolutely. But Humans and most Sentience are far more emotional overall.
Known Feats of Magic
A known practitioner of Will Magic was the ancient Elf, Dorst Valnir, who was able to make a storm of immeasurable strength cease in seconds.
Another time the man was said to grow a forest utilizing, just a few seeds, in less than an hour. The forest was said to stand stronger and taller than any other.