The Loosing of the Shadow

...
“Don't be afraid,” he said, smiling. “I'll call a woman's spirit. You need not fear a woman. Elfarran I will call, the fair lady of the Deed of Enlad.”
“She died a thousand years ago, her bones lie afar under the Sea of Ea, and maybe there never was such a woman.”
“Do years and distances matter to the dead? Do the Songs lie?” Ged said with the same gentle mockery, and then saying, “Watch the air between my hands,” he turned away from the others and stood still.
In a great slow gesture he stretched out his arms, the gesture of welcome that opens an invocation. He began to speak.
He had read the runes of this Spell of Summoning in Ogion's book, two years and more ago, and never since had seen them. In darkness he had read them then. Now in this darkness it was as if he read them again on the page open before him in the night. But now he understood what he read, speaking it aloud word after word, and he saw the markings of how the spell must be woven with the sound of the voice and the motion of body and hand.
The other boys stood watching, not speaking, not moving unless they shivered a little: for the great spell was beginning to work. Ged's voice was soft still, but changed, with a deep singing in it, and the words he spoke were not known to them. He fell silent. Suddenly the wind rose roaring in the grass. Ged dropped to his knees and called out aloud. Then he fell forward as if to embrace earth with his outstretched arms, and when he rose he held something dark in his straining hands and arms, something so heavy that he shook with effort getting to his feet. The hot wind whined in the black tossing grasses on the hill. If the stars shone now none saw them.
The words of the enchantment hissed and mumbled on Ged's lips, and then he cried out aloud and clearly, “Elfarran!”
Again he cried the name, “Elfarran!”
The shapeless mass of darkness he had lifted split apart. It sundered, and a pale spindle of light gleamed between his opened arms, a faint oval reaching from the ground up to the height of his raised hands. In the oval of light for a moment there moved a form, a human shape: a tall woman looking back over her shoulder. Her face was beautiful, and sorrowful, and full of fear.
Only for a moment did the spirit glimmer there. Then the sallow oval between Ged's arms grew bright. It widened and spread, a rent in the darkness of the earth and night, a ripping open of the fabric of the world. Through it blazed a terrible brightness. And through that bright misshapen breach clambered something like a clot of black shadow, quick and hideous, and it leaped straight out at Ged's face.
Staggering back under the weight of the thing, Ged gave a short, hoarse scream. The little otak watching from Vetch's shoulder, the animal that had no voice, screamed aloud also and leaped as if to attack.
...

A sample from The Wizard of Earthsea by Ursula K. Le Guin