Dragonlords magic

Dragons and Dragonlords can use a particular type of magic. It's likely that even this form of power comes from the Old Religion, but it's different from the magic used by most human sorcerers.

Dragons are probably the most powerful magical creatures of all, and have the greatest magical knowledge and ability. They can pass the extremely effective spells they know to humans with their mind. Kilgharrah showed Merlin two enchantments, one to trap Cornelius Sigan's soul back in his jewel (who was the most powerful sorcerer of the Old Religion ever to live) (The Curse of Cornelius Sigan), and then an healing spell to cure Morgana of her fatal cranium wound (The Crystal Cave).

Dragonlords have access to this form of magic when they inherit their fathers' powers. They can speak in the dragon tongue, and cast special spells in it. The known characteristics of dragonlords magic are:
 * The ability of speaking to any dragon in the language shared by their souls. The dragonlords can use this power to force tasks upon dragons, and command them to do whatever they wanted. Merlin tamed the Great Dragon with this spell, forcing him to stop attacking Camelot: "Dragorn. Non didlkai. Kari miss, epsipass imalla krat. Katostar abore ceriss. Katicur. Me ta sentende divoless. Kar… krisass" (The Last Dragonlord). They also have a certain power over wyverns, for they were distant cousins of the dragons. Merlin used two different spells, spoken in the dragon tongue, to send away the wyvers: once while he was protecting Arthur in the Fisher King's Dark Tower ("Nun de ge dei s'eikein kai emois epe'essin hepesthai") (The Eye of the Phoenix), and the other when he drove them away on the Isle of the Blessed ("S'enthend' apokhorein nun epello-o-o") (The Darkest Hour: Part Two).
 * They can summon dragons and make them come to their rescue. Merlin used a spell ("O drakon, e mala soi ftengometh tesd'hup anankes! Erkheo") to call Kilgharrah in different occasions (The Tears of Uther Pendragon: Part One, The Sorcerer's Shadow, The Darkest Hour: Part Two).
 * The ability of casting a form of stunning spell by emitting a great roar that sounds like a Dragon's (The Tears of Uther Pendragon: Part One).
 * Only a dragonlord can cause a dragon egg to hatch, calling them from their dormant state and out of the shell, by giving the baby dragon a name. Merlin gave life to Aithusa, naming him, in the dragon tongue, after the "light of the sun" (Aithusa).