Centaur Aisle by Piers Anthony

solved.
    Then a huge old rock-maple tree fell across one of the magic paths leading to Castle Roogna. This was a well-traveled path, and it was not safe to leave it, for beyond its protection the nickelpedes lurked. No one would risk setting foot into a nickelpede nest, for the vicious little creatures, five times the size and ferocity of centipedes, would instantly gouge out nickels of flesh. The tree had to be cleared—but the rock was far too heavy for any ordinary person to move.
    Smash the Ogre took a hammer, marched down the path, and blasted away at the fallen trunk. He was as yet a child ogre, not more than half again as tall as Dor, so possessed of only a fraction of his eventual strength, but an ogre was an ogre at any age. The hummer clanged resoundingly, the welkin rang, the stone cracked asunder, dust flew up in clouds that formed a small dust storm wherein dust devils played, and fragments of maple shot out like shrapnel. Soon the little ogre had hewn a path-sized section through the trunk, so that people could pass again. The job had been simple enough for him, though as an adult, he would not have needed the hammer. He would merely have picked up the whole trunk and heaved it far away.
    So it went. Another week passed—and still King Trent and Queen Iris did not return. Irene's nervousness was contagious. "You've got to do something, Dor!" she screamed, and several ornamental plants in the vicinity swelled up and burst, responding to her frustration.
    "The Elders won't let me go after him," he said, as nervous as she.
    "You do something right now, Dor, or I'll make your life completely miserable!"
    Dor quailed anew. This was no empty bluff. She could make him miserable on her good days; how bad would it be when she really tried? "I'll consult with Crombie," he said.
    "What good will that do?" she demanded. "My father is in Mundania; Crombie can't point out his location beyond the realm of magic."
    "I have a feeble notion," Dor said.
    When Crombie arrived, Dor put it to him: how about pointing out something that would help them locate King Trent? Crombie could point to anything, even an idea; if there were some device or some person with special information—
    Crombie closed his eyes, spun about, flung out one arm, and pointed south.
    Dor was almost afraid to believe it. "There really is something that will help?"
    "I never point wrong," Crombie said with certainty. He was a stout, graying soldier of the old school, who had a wife named Jewel who lived in the nether caves of Xanth, and a daughter named Tandy of whom no one knew anything. Jewel had been a nymph of the rock; it was her job to salt the earth with all the diamonds, emeralds, sapphires, rubies, opals, spinels, and other gemstones that prospectors were destined eventually to find. She was said to be a lovely, sweet, and tolerant woman now, satisfied to see Crombie on those irregular occasions when he got around to visiting her. Dor understood that Jewel had once loved his father Bink, or vice versa— that had never been made quite clear—but that Crombie had captured her heart with a wish-spell. Love had transformed her from nymph to woman; that process, too, was not quite within Dor's comprehension. What was the distinction between a nymph and a girl like Irene? "Sometimes people interpret it wrong, but the point is always right," Crombie finished.
    "Uh, do you have any idea how far it is?"
    "Can't really tell, but pretty far, I think. I could triangulate for you, maybe." He went to another room of the castle and tried again. The point remained due south. "Too far to get a proper fix. Down beyond Lake Ogre-Chobee, I'd say."
    Dor knew about that lake; it had been part of the geography Cherie Centaur had drilled into him. A tribe of fiends lived beneath it, who hurled curses at anyone who bothered them; they had driven off most of the ogres who had once resided on its shores. A number of those displaced ogres had migrated north, settling in the