Roland mentally resists an oracle (succubus)

He stepped into the clearing and walked straight into the circle. He stood, letting his mind run free. Yes, it was coming harder now, faster. The grass screamed green at him; it seemed that if he bent over and rubbed his hands in it he would stand up with green paint all over his fingers and palms. He resisted a puckish urge to try the experiment.
But there was no voice from the oracle. No stirring, sexual or otherwise.
He went to the altar, stood beside it for a moment. Coherent thought was now almost impossible. His teeth felt strange in his head, tiny tombstones set in pink moist earth. The world held too much light. He climbed up on the altar and lay back. His mind was becoming a jungle full of strange thought-plants that he had never seen or suspected before, a willow-jungle that had grown up around a mescaline spring. The sky was water and he hung suspended over it. The thought gave him a vertigo that seemed faraway and unimportant.
A line of old poetry occurred to him, not a nursery voice now, no; his mother had feared the drugs and the necessity of them (as she had feared Cort and the need for this beater of boys); this verse came from the Manni-folk to the north of the desert, a clan of them still living among machines that usually didn’t work . . . and which sometimes ate the men when they did. The lines played again and again, reminding him (in an unconnected way that was typical of the mescaline rush) of snow falling in a globe he had owned as a child, mystic and half fantastical:
Beyond the reach of human range   A drop of hell, a touch of strange . . .
The trees which overhung the altar contained faces. He watched them with abstracted fascination: Here was a dragon, green and twitching, here a wood-nymph with beckoning branch arms, here a living skull overgrown with slime. Faces. Faces.
The grasses of the clearing suddenly whipped and bent.
I come.
I come.
Vague stirrings in his flesh. How far I have come, he thought. From lying with Susan in sweet grass on the Drop to this.
She pressed over him, a body made of the wind, a breast of fragrant jasmine, rose, and honeysuckle.
“Make your prophecy,” he said. “Tell me what I need to know.” His mouth felt full of metal.
A sigh. A faint sound of weeping. The gunslinger’s genitals felt drawn and hard. Over him and beyond the faces in the leaves, he could see the mountains—hard and brutal and full of teeth.
The body moved against him, struggled with him. He felt his hands curl into fists. She had sent him a vision of Susan. It was Susan above him, lovely Susan Delgado, waiting for him in an abandoned drover’s hut on the Drop with her hair spilled down her back and over her shoulders. He tossed his head, but her face followed.
Jasmine, rose, honeysuckle, old hay . . . the smell of love. Love me.
“Speak prophecy,” he said. “Speak truth.”
Please, the oracle wept. Don’t be cold. It’s always so cold here—
Hands slipping over his flesh, manipulating, lighting him on fire. Pulling him. Drawing. A perfumed black crevice. Wet and warm—
No. Dry. Cold. Sterile.
Have a touch of mercy, gunslinger. Ah, please, I cry your favor! Mercy!
Would you have mercy on the boy?
What boy? I know no boy. It’s not boys I need. O please.
Jasmine, rose, honeysuckle. Dry hay with its ghost of summer clover. Oil decanted from ancient urns. A riot for flesh.
“After,” he said. “If what you tell me is useful.”
Now. Please. Now.
He let his mind coil out at her, the antithesis of emotion. The body that hung over him froze and seemed to scream. There was a brief, vicious tug-of-war between his temples—his mind was the rope, gray and fibrous. For long moments there was no sound but the quiet hush of his breathing and the faint breeze which made the green faces in the trees shift, wink, and grimace. No bird sang.
Her hold loosened. Again there was the sound of sobbing. It would have to be quick, or she would leave him. To stay now meant attenuation; perhaps her own kind of death. Already he felt her chilling, drawing away to leave the circle of stones. Wind rippled the grass in tortured patterns.
“Prophecy,” he said, and then an even bleaker noun. “Truth."
-The Gunslinger